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Manga / Assassination Classroom

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We are assassins; our target is our teacher.

"A group of junior high school students are joyfully discussing an assassination. If you look at it normally, this is the pinnacle of madness."
Tadaomi Karasuma

Every morning, the students of Kunugigaoka Middle School's Class 3-E greet their homeroom adviser—a yellow, grinning, octopus-like being—with a massive firing squad.

This creature was responsible for blowing up 70% of the Moon, rendering it permanently crescent-shaped, and is threatening to do the same to Earth in exactly one year. But now he has grown bored of the world governments' futile attempts at killing him, so he strikes them an odd deal: permit him to be Class 3-E's homeroom teacher, and he'll allow the students to try and kill him however they'd like to. Can the students successfully take him, now named "Koro-sensei", down and save the world despite the fact that he's ridiculously fast (so much so he can hit Mach 20), very cunning, nearly invincible, and definitely the best teacher they've ever had—especially for an infamous class of twenty-six social misfits and academic underachievers whom society has given up on?

Despite the outlandish and somewhat foreboding premise, Assassination Classroom (暗殺教室 Ansatsu Kyōshitsu) is a lighthearted, action-packed comedy with several realistic, Slice of Life elements woven into its story. Imagine a less explicit Great Teacher Onizuka mixed with sci-fi and espionage to get an idea of what you're in for.

The author, Yuusei Matsui, is also the creator of Majin Tantei Nougami Neuro, which deals with similar ideas, mainly a supernatural creature with Blue-and-Orange Morality who's ultimately bettering the people it comes across. The difference is where Neuro was protecting his food source, Koro-sensei is trying to better his students by working in the killing arts as a teaching tool. And it works. Of course, there is the slight problem of him planning to destroy the world...

Assassination Classroom was serialized in Weekly Shonen Jump from 2012 to 2016 for 187 chapters, which were compiled into 21 volumes (notably, it did not fall below 4th place in the Weekly Shonen Jump TOC rankings once over its entire duration). The manga is licensed in English by VIZ Media and released under their Shonen Jump imprint.

Two OVAs premiered during the 2013 and 2014 Jump Special Anime Festa tours: the 2013 OVA adapts the Kyoto field trip arc, while the 2014 OVA, titled Episode 0: Encounter Timenote  (Episode:0 出会いの時間 Deai no Jikan), details how Koro-sensei and Karasuma first met. Afterwards, a two cour TV anime adaptation produced by Lerche premiered on January 9, 2015, with its second season debuting a year later on January 7, 2016. The Episode 0 OVA was included as bonus content for the anime's first home video release. Funimation has picked up the rights to stream and dub the anime. The show made its American television premiere on [adult swim]'s Toonami block on August 29, 2020. In Australia, SBS 2 is airing the anime.

The series also has a non-canonical Spin-Off entitled Koro-Sensei Quest!. Basically imagine the plot in an RPG Mechanics 'Verse.

A Live-Action Adaptation film called Assassination Classroom produced by Toho was released in Japan on March 21, 2015, and roughly covers the first half of the story. A sequel called Assassination Classroom: Graduation (暗殺教室 卒業編 Ansatsu Kyōshitsu: Sotsugyō-hen) was released on March 25, 2016, and covers the latter half.

A video game called Assassination Classroom: Koro-sensei's Great Besiegement!! (暗殺教室 殺せんせー大包囲網!! Ansatsu Kyōshitsu: Koro-sensei Dai Hōimō) developed by Bandai Namco Entertainment for the Nintendo 3DS was released in 2015.

Koro-sensei appears as a playable character in J-Stars Victory VS, originally released in Japan for PlayStation 3 and Play Station Vita in 2014 and internationally in 2015.

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  • 13 Is Unlucky: If one looks closely at the student body assembly in Season 1 Episode 5, not counting Class 3-E each year has four sections for a total of twelve. Class 3-E is thus the thirteenth section, reinforcing its reputation as the dumping-ground for Kunugigagoka's worst of the worst.
  • Aborted Declaration of Love:
    • Despite being a professional at the art of seduction, Irina fails to fully confess her feelings towards Karasuma. Her students don't take this too well.
    • Kayano tries to confess to Nagisa on Valentine's Day, even giving Koro-sensei a chocolate with a picture of her late sister Aguri in a bikini enclosed in it just to distract him long enough to not snoop in on it, but she decides not to for the time being.
  • Absurdly Divided School: The main plot is that the sociopathic headmaster of an elite private school keeps grades up by segregating the academically under-achieving in a tumbledown shack a long way from the main building, instituting rules designed solely to inconvenience and humiliate them, and encouraging the other pupils to hate and despise them.
  • Abusive Parents:
    • The entire reason Nagisa is capable of reading people so easily with a single glance is because he had to in order to survive his mentally unhinged mother Hiromi, who can go from zero to psycho in the blink of an eye. She also constantly tells him she wishes he was born a girl and makes him grow his hair long, despite the fact that he hates it, which could cast all previous jokes about his androgyny in a harsher light. His father isn't much better, but his is more of the Parental Neglect variant, because despite knowing how violent Hiromi can be, he just pretty much left Nagisa to deal with it alone, only showing up once in a while (though the Graduation Book Time reveals that Nagisa living with his mother is entirely of his own free will).
    • Principal Asano is one of the emotional variety to his son Gakushuu, needing little prompting to rattle about how all of his son's plans ended up in failures. Gakushuu usually responds in kind but it's clear his father terrifies him sometimes (just look at Gakushuu's face when his father beats up the foreign students who were defending him.). Also, Gakushuu's been slapped by his father at least once (by pointing out how his plans ended in failure, ironically enough).
  • Action Bomb: Deconstructed in the very first chapter, when Nagisa tries to blow up Koro-sensei at point-blank range using a makeshift pellet grenade hidden around his neck. This makes Koro-sensei absolutely furious, even though he (and Nagisa, for that matter) escapes unscathed. Surprisingly, he isn't outraged over the fact that he was almost duped by a mere student—in fact, he praises the plan for its ingenuity and Nagisa in particular for flawlessly executing it. What disgusted Koro-sensei was that Terasaka, the student who came up with the plan, coerced Nagisa into doing it for him despite the high risk of the boy getting injured in the process.
  • Actor Allusion: Yuzuki Fuwa shares the same voice actress and character type of Yako Katsuragi, the heroine and kid detective of the author's previous series. In Episode 19, after deducing who poisoned her classmates, Fuwa mimics Yako's modus operandi by dramatically pointing at him and shouting, "The culprit was you!"
  • Adaptational Hairstyle Change: In the live action movies:
    • Nagisa has shoulder-length hair that he ties into pigtails in the source material, but he has short boyish hair in the live action movies. Incidentally, Nagisa's mother (who forced him to have long hair) is absent from the movies.
    • Aguri Yukimura has short hair in the manga and the anime, but in the live-action movies she has long hair that goes over her shoulders.
  • Adaptation Distillation:
    • The anime had to remove some comedic moments and minor information about some of the characters from the manga to ensure they could fit in at least 2-3 chapters in one episode. The second season takes this further, truncating the manga's longer arcs (4-5 chapters per episode) so that they can be made into 1-2 episodes.
    • The live action movies only kept some key moments from the manga due to their two-hour-length time restraints. Similar to how it was handled in the anime, the first movie dealt up until the Island Arc (only changing the setting in the old campus, and putting Itona in there as well, as part of Takaoka's threat), and the sequel (properly subtitled "Graduation") did all the way up until the series' finale.
  • Adaptation Dye-Job: The live-action movie subjected this to a lot of characters, including Nagisa and Kayano. Karma, oddly enough, still has his red hair.
  • Adaptation Expansion: The anime rearranges a few of the manga's arcs in order to streamline the flow of the story. It also throws in a few small scenes to give the cast some extra tidbits of characterization. Several of these extra scenes were inspired by the extra bonus content included within the series' volume releases.
  • Adaptation-Induced Plot Hole: As mentioned above in Adaptation Dye-Job, Kayano's hair is brown instead of green in the live-action movie. This creates a plot hole after The Reveal that she's actually a moderately-famous actress. In the manga, nobody recognized her because she dyed her hair green, so it begs the question how nobody in the movie recognized her.
  • Adapted Out:
    • Several chapters that provide characterization for the supporting classmates were left out of the anime adaptation.
      • Maehara's limelight chapters (23 and 24) that establishes him as the class casanova seem to have been removed from the anime entirely. One can only imagine it had something to do with the whole "poisoning your schoolmates" thing.
      • Sousuke's limelight chapter (37), which shows off his artistry, also got skipped.
      • Meg's limelight chapters (44 and 45) that deals with an issue of a school student abusing Meg's generosity also didn't make the cut.
      • Craig Houjou is left out of the anime adaptation, being replaced by a generic military commander. The subplot of Class 3-E being kidnapped by Houjou and his men is also skipped.
    • The live action movie duology had to massively streamline the manga's story in order to fit into a combined 4 hours of runtime; thus, numerous story arcs and characters such as Asano Jr., the Five Virtuosos, Smog, Grip, Gastro, Nagisa's mother, and the Reaper are omitted. Chairman Asano is also Demoted to Extra in the first movie, and is absent in the second movie altogether. Weirdly enough, unlike in the anime, Craig Houjou does appear in the second movie.
  • All There in the Manual: The Official Character Guide reveals a fair bit of information about the students, particularly relationship wise.
  • Animal Motifs:
    • Creepy Centipedes for the Chairman and his son, a metaphor of their controlling nature.
    • Koro-sensei with octopods, since both are slithery intelligent tentacled creatures. This one is often invoked by Koro-sensei himself, as he sometimes draws himself as an octopus when grading his students' papers, among other things.
    • Nagisa with a snake, as a metaphor of his ability to hide murderous intent in plain sight.
  • Answer Cut: In Chapter 52.
    "There isn't a single student stronger than him in this school." [speaking with regards to the Chairman's son]
    [cut to a yawning Karma]
  • Antagonist Title: At first, Episode 21 is called "XX Time". However, once the true mastermind behind the Assassination Island arc is revealed to be Akira Takaoka, the true title of the episode is "Takaoka Time".
  • Apocalypse How: Class X. Imminent destruction of Earth if Koro-sensei is not stopped.
  • Applied Phlebotinum: The guns, grenades, knives, bullets, etc. used by the students are made of a specially-made substance harmless to humans, but on contact cause Koro-sensei's cells to break down.
  • Arc Symbol: The permanent crescent moon, symbolizing Koro-sensei, often serving as a reminder of just how powerful he is. It is revealed much later that Koro-sensei had appropriated the crescent moon for himself as he took the blame for the moon's destruction, having sewed the symbol on his tie. Additionally, as Nagisa notes in the epilogue, after Koro-sensei's death, the crescent moon slowly coalesces back into a sphere thanks to gravity; in essence, the crescent moon "died" with him.
  • Arc Words:
    • "The tentacles asked [me], 'What would you like to be?' [I] answered..." becomes one later in the series. It's used by every character that acquired tentacles in summation of their flashbacks explaining what led to them seeking the power they provide.
    • The "we are assassins and our target is our sensei" internal speech shows up a lot as well, especially early on. And gets a heartbreaking reprise in the final.
  • Artistic License – Geography: The "Koro-sensei Drawing Song" shows Koro-sensei drawing his trademark smile by leaving contrails from Dubai to Hawaii and then back again, passing the Philippines along the way. Although the manga depicts this accurately, in the anime, he actually crosses Indonesia on his return trip instead of the Philippines.
  • Artistic License – Gun Safety: Mostly averted, except for a few instances of lax trigger discipline. The anime even clears those up.
  • Artistic License – Law: Class A's elites mention some 50 contractual traps in their betting agreement with Class E. Absolutely bulletproof... except the minimum age for legal agreements in Japan is 20. This age requirement also applies to gambling.
  • Artistic License – Physics:
    • Koro-Sensei moving around at several times the speed of sound should cause immense winds that would swiftly destroy the classroom and everything in it, but usually it only makes the students' hair flutter.
    • It's stated in the series that Mach 20 is "twice the speed of sound". Mach 1 is the speed of sound, so Mach 20 would be twenty times faster.
  • Assassin Outclassin': Naturally, or the series would be over before hitting the third page of the first chapter.
  • A-Team Firing: The opening of the story begins with the entire class trying to gun Koro-sensei down. Not only does this fail, but Koro-sensei continues as if nothing were happening, taking attendance as the class continues shooting. The only notice he takes is when he asks a student to speak up, since he can't hear well over the gunfire.
  • Award-Bait Song: The second ending theme of Season 2, "Mata Kimi ni Aeru Hi" ("Until the Day I See You Again"), as well as the insert song for Season 2 Episode 4, "Tabidachi no Uta" ("Journeying Song").
  • Axes at School: They're rubber knives and pellet guns that are only harmful to Koro-sensei, but they're still rather alarming.
  • Bad Powers, Good People: Invoked by Koro-sensei, who teaches Class 3-E how to benefit their lives with the mindset of the assassin.
  • Bait-and-Switch: In Episode 18, during a video made to distract Koro-Sensei out of embarrassment, it's said that he takes rigorous advantage of free tissue samples, and considering the kinda guy he is, one probably wouldn't expect him to fry them... for whatever reason.
    • When Takebayashi temporarily joins Class A, his fellow students take note of his shocked face at the teacher's math lesson. They assume (much like the reader might) that he is overwhelmed by how fast and intense the trigonometry lecture is, but his internal monologue reveals that he's actually astonished at how incompetent the teacher is compared to Koro-sensei, noting that Class E already covered trigonometry last semester.
  • Baseball Episode: Episode 12 (Chapters 33-36) has the Class 3-E boys going up against the school baseball club team in the annual exhibition match typically used to humiliate them. Thanks to Koro-sensei's training, however, Class 3-E manages to turn the match in their favor, gaining 3 points in the first round and forcing Chairman Asano to step in and coach the baseball club team himself.
  • Batman Gambit: Azusa pulls this on Korosensei in the extra chapters to lure him into an assassination. After discovering that she has an inoperable brain tumor, she learns about Korosensei from the four assassins who frequent her pub. She then purposefully signs a contract with loan sharks that ends up getting her kidnapped, forcing the assassins and Korosensei to rescue her. After the rescue, she planned to blow up the building to either kill Korosensei and leave the money to her daughter; or, if Korosensei didn't show up, to kill the loan sharks, erase her debt, and protect her daughter, while leaving her daughter with a considerable amount of money from the life insurance she took out on herself.
  • Beach Episode:
    • In Chapter 43, Koro-sensei builds a pool for the students so they can find relief from the summer heat. Ties in to the main plot when it leads to them discovering that Koro-sensei can't swim.
    • Season 1 of the anime closes with the students enjoying the last evening of their island vacation by having fun at the nearby beach.
  • Beauty Equals Goodness: If you're attractive (or at least ordinary) without looking downright creepy, then you're likely a member of Class-E in one way or another. The only exception to this seems to be Koro-sensei and the four 3-E delinquents (not counting Karma). It's even lampshaded when two girls in a higher-ranking class note that 3-E's PE teacher, the young government agent Karasuma, is rather attractive, and that all of the guys and teachers in their class are ugly and mean.
    • Koro-sensei's appearance plays with this trope. His face will change from "good" to "evil" (pitch black for extreme anger) if anyone tries to push his button (hurting his students or seeing Itona Horibe's tentacles. Then inverted with his original, human appearance, which shows that he used to be a pretty handsome man before the experiments he endured turned him into the creature he is today.
    • Averted with Kaho Tsuchiya of 3-C. Beautiful? Yes. Cold-hearted, manipulative, vile witch? An undisputed affirmative. Played straight when she shows her true face.
    • Played With in Takaoka: his cartoony (well, more cartoony) smiley face masks a vicious streak a mile wide.
    • The doctor (Shiro) who turned an extremely skilled but still human assassin into the superhuman Koro-sensei looks rather attractive at first; then he starts referring to his secret human test subject as a disposable guinea pig ("he doesn't have a family registry so it doesn't matter if he dies"), smashes a vial of something on an assistant's head, and strikes his other assistant/slave/wife via arranged pity-marriage on the head with a computer tablet repeatedly. By the time the (first/original) God of Death KO's him through a solid plexiglass barrier his good looks have gone a bit off.
  • Berserk Button:
    • Kaede Kayano hates big boobs because she is insecure about her own size, and will often get upset whenever big boobs are brought into her attention.
    • A cultural one, for Brazil: "7 to 1". Triggered accidentally when Koro-sensei tries coming up with math problems while vacationing there.
  • Better to Die than Be Killed: In Chapter 176, Koro-sensei asks the students to kill him before the government's Kill Sat can. His students agree, as they believe it's better for Koro-sensei to die by their hand than by anybody else's. When he asks Irina to assist, she respectfully declines.
  • Big Bad: Shiro is the most recurrent antagonist Koro-Sensei and his students face over the course of the series, earning this spot by default. Then it's solidified when it's revealed that he's really Yanagisawa, the Mad Scientist who transformed Koro-Sensei from a human into what he now is, making him responsible for the whole series in the first place. Then he and the God of Death, who he makes his Dragon, jointly serve as the Final Boss at the series' climax.
  • The Big Damn Kiss: Nagisa pulls a 15-hit combo French kiss on Kayano in order to knock her out so that Koro-sensei can remove her tentacles.
  • Big Entrance: When The Final Question arrives at the very end of the second term finals, it does not do so subtly. The manga merely has it flying in, smashing its way into the imaginary arena. But in the anime, it arrives through a giant black hole in the sky that spits out lightning everywhere, surrounded by a halo of flames. Everyone but Karma and Gakushuu can only look on in awe. this is an appropriate visual metaphor for reaching the very end of a test and suddenly coming upon a question miles above the level you've studied for, which is worth a fifth of your grade in that subject.
  • Bittersweet Ending: Koro-sensei finally dies at the hands of Class 3-E after killing the second Reaper, his treacherous ex-apprentice; and brutally maiming Yanagisawa, the scientist who turned him into what he is now. However, far from celebrating having saved the world, they instead mourn him after spending a year developing intellectually, physically and emotionally under his tutelage (made all the more heartbreaking by the fact that killing him was already largely optional at that point, as his chances of blowing up were actually 1%, but they were forced to do what they had to before a government Kill Sat did so). Nevertheless, all 28 students graduated with newfound confidence and sense of self-worth, ready to apply their lessons to lead better adult lives.
  • Black Comedy Rape: Subverted in Chapter 9 / Season 1 Episode 4, when Koro-sensei decides to retaliate against Irina's failed assassination attempt with some "maintenance". It turned out to be nothing but a high-speed massage, a swift change into a more conservative outfit, and something else...
  • Blaming the Victim: Kunugigaoka divides third-year students into A, B, C, D and E classes based on grades, with the Class E students having the lowest grades and being placed in a separate campus away from the main school with sub-par resources. No concessions are made for students no matter their reasons for having poor grades, meaning many of the Class E students are perfectly intelligent and capable, yet are essentially punished for circumstances out of their control.
  • Bland-Name Product: In Chapter 2, the K.Y. Times for the New York Times, and the Turkies for the New York Yankees. The Pocky seen throughout the series is known as Pooky. There's also 5 Up soda, Jac Danas whiskey, and Void brand computers.
  • Blinded by the Light: During the battle at the concert hall, Gastro cranks up the stage lights behind him to make it hard for the kids to properly aim their guns at him.
    • The final battle has this as one of the ways to make it harder for Koro-sensei. It seems to work at first until he stops the blinding flash by throwing dirt.
  • A Bloody Mess: During Karasuma's fight against the Reaper, the latter uses his Finger Firearms to shoot directly at Karasuma's chest, causing blood to spill from his heart. Except as it turns out, Koro-sensei manages to slip one of his tentacles through his cell and protect Karasuma just in time, pumping tomato juice through the tentacle as a decoy for spilled blood. Karasuma then proceeds to kick the Reaper in the balls.
    Reaper: You faked me out with tomato juice?!
  • Book and Switch: During Class 3-E's study session in the library, Kayano uses a textbook to hide the "Puddings of the World" book she's actually reading.
  • Book Ends:
    • The series begins with Koro-sensei taking a roll of Class 3-E while they're firing at him. The final arc has a double-book-end: Chapter 177 / Season 2 Episode 24 has him roll-calling the class one last time before they finally assassinate him. Then the whole series ends with Nagisa, now a collegiate intern working part-time teaching to a classroom of delinquents, designated Class 3-5 (a subtle nod to his old class also being the fifth third-year class of Kunugigaoka), calmly confronting his students before taking a roll-call.
    • Both the first chapter and the final Extra Chapter involve attempting to kill Koro-sensei with a grenade.
    • To a lesser extent, Season 1 is book-ended with class bully Ryouma Terasaka's interaction with Nagisa, displaying the former's Character Development. The series began with him coercing Nagisa into becoming a suicide bomber against Koro-sensei. Episode 22 ends with him warning Nagisa against going into a murderous rampage against Takaoka.
    • The beginning of the story has the moon exploding and turning into a crescent shape as the plot kicks off. The end has it collapse in on itself and move closer to earth, gradually returning to its original appearance.
  • Both Sides Have a Point: In the A House Divided situation both groups of students have a good reason for their choice. The group that wants to save Koro-sensei thinks they can't kill him after all they've been through and should therefore try to save him and the world. The group that wants to still try to kill him is worried about what happens if they cannot find a way to save Koro-sensei and the fact that by killing him they'd be following his own expressed wishes.
  • Bread, Eggs, Milk, Squick: Nagisa idly chats with Kayano and says that in the coming school year, he'd like to get to know everyone in class 3-E, live his life without leaving things undone, and kill their teacher.
  • Breaking the Fourth Wall:
    • In Chapter 22, after Takebayashi states that girls don't need any more than two dimensions.
      "Takebayashi, do you seriously want that to be your first line in this manga?!"
    • Everything Fuwa says. Everything. Her classmates have noticed this — in the nickname chapter, she gets dubbed "This Manga Is Awesome!"
    • In Chapter 155, Koro-sensei is seen messing around with speech and thought bubbles.
    • In the English dub, when the class sings Happy Birthday to You! to Koro-sensei, Terasaka wonders if they even have the legal rights to do it.
  • Breather Episode:
    • After the intensity of the Assassination Island arc, Koro-sensei decides to spend their remaining time on Fukuma Island by treating the kids to a test of courage.
    • After the Second Semester Exam arc, the next chapter focuses on 3-E putting on a hilariously dark play. The chapter after that is Chapter 128.
    • Following the tension of the civil war game, the subsequent reconciliation and an audacious space trip to retrieve data that could help Koro-sensei, Class 3-E takes some time off during Valentine's Day to spend time interacting with each other.
  • Brick Joke: The cellphone pictures Karma and Nakamura took of Nagisa and Kayano's Big Damn Kiss make a comeback in Chapter 159 when they show it to an unsuspecting Kayano. Her reaction was hilarious.
  • Bullet Catch: Being able to move at Mach 20, Koro-sensei does this frequently.
    • In the first chapter, he catches a bullet from Nakamura using two pieces of chalk.
    • During the Kyoto field trip, he somehow manages to catch Red Eye's sniper bullet using a piece of yatsuhashi — a soft confectionery made with glutinous rice flour.
    • In the Episode 0 OVA, Karasuma attempts to assassinate Koro-sensei by shooting at him, but the latter manages to avoid the bullets thanks to his speed, and even catches one of them with his bare tentacle.
  • Call-Back: There are numerous little details that become relevant dozens of chapters later.
    • All the way back in Chapter 2, Nagisa's English journal entry mentions sushi is his and his father's favorite food. In Chapter 76, the two of them have breakfast together at a sushi bar.
    • In Chapter 51 / Season 1 Episode 15, Kayano reads a magazine on "Puddings of the World" instead of studying for finals. Her assassination attempt in Chapter 80 / Season 2 Episode 2 involves making a gigantic, explosive pudding.
    • The "weasel" which appears in the end of Chapter 56 returns in Chapter 88 to destroy the mini-tank of the boys.
    • Nagisa and Karma think back to the time they were nervous about flying in Koro-sensei's robe before their even more insane trip into space on an experimental rocket.
    • Koro-sensei had made thousands of embarrassing photographs. While some are new to the audience, many are a flashback to awesome and heartwarming moments from the story. And then he spends his supposedly final moments organizing them into a ten thousand page graduation album...
    • In the very first chapter, Nagisa attempts to kill Korosensei with a grenade at close range. Miss Azusa attempts the same thing in Extra Chapter 3.
    • During Takebayashi's mini arc, it is mentioned that a student once broke some stuff in the headmaster's office and was sent to Class E immediately, which Takebayashi uses for his own advantage. Many chapters later it is revealed that the student mentioned in the story was Kayano.
  • Cast Of Snow Flakes: No two major characters look alike.
  • Casting Gag:
    • In the anime adaptation, Kana Ueda voices Yuzuki Fuwa, the Class E student with a knack for mystery solving. She previously voiced Yako Katsuragi, the amateur detective and heroine of the author's previous series.
    • Robot Girl Ritsu is played by Saki Fujita, who lent her voice to the most famous Vocaloid, Miku Hatsune.
    • Terasaka is purposely similar in some aspects to Doraemon's Gian, and they ended up sharing the same voice actor, Subaru Kimura.
    • Asano Gakushuu shares the same voice actor as well as characteristics as another famous genius.
  • Cerebus Retcon:
    • Nagisa's androgynous appearance is at first played for laughs, often leading to him being cross-dressed. Then we find out that his controlling Abusive Mom forces him to dress as a girl. While she does not stop, Nakamura, who often teases Nagisa and forces him into girl's clothes, is horrified and apologises.
    • Despite being a seemingly all-powerful tentacled creature, Koro-sensei has many, many weaknesses, most of which are comical for someone like him to have (he panics and gets flustered easily, he's a horndog, he can't move if all his tentacles are pinned down, etc.). Much later in Chapter 140, we learn that he actually became Willfully Weak, to atone for his destructive rampage which inadvertently led to Aguri's death, as well as to best pursue his goal of teaching Class 3-E in Aguri's stead.
      Koro-sensei: The tentacles asked me what I wanted to be. I want to be weak. To be riddled with weaknesses, easy to talk to. To be able to perceive the weak, to protect them, to guide them... To be that kind of creature, that kind of teacher. Sometimes I'll be wrong. Sometimes my cold-hearted true face might even show. But I'll give it my all. I'll aim for her goal in my own way, the way I do best.
  • Cerebus Syndrome: Though there are still many moments of comedy, as the series reaches its last half, the tone gradually gets darker, with Koro-sensei's explosion looming on the horizon. Notable incidents include the raid on the Fukuma Palace Hotel to find an antidote for an (apparently) lethal virus that has affected some of the students and the first appearance of the Reaper. Then things get bleaker with the revelations of Kayano's true identity and Koro-sensei's tragic past, leading to internal strife which led to a civil war game. Then, after a brief respite with the Valentine's Day arc, the government, implicitly under the thrall of Shiro/Yanagisawa, concocts a failsafe plan to assassinate Koro-sensei, forcing the class to go through with their deal with Koro-sensei and finally kill him. Even the opening themes between both seasons reflect the shifting tone — cheerful in the first, melancholy in the second.
  • Chainmail Bikini: Irina had initially suggested a sexier, more revealing look when coming up with the design for the female students' new P.E. uniforms. The students complain that the skimpy design would've reduced most of its defensive capabilities to zero.
  • Chekhov's Gag:
    • At the beginning of the series, Irina tries to extract some information out of Nagisa by planting a 30-hit French kiss on him. Several months later, Nagisa uses the exact same technique on Kayano to distract her from the destructive influence of her tentacles. He only lands 15 hits, but it's more than enough to distract her long enough for Koro-sensei to remove her tentacles.
    • Remember the formula Koro-sensei made with Okuda that gave him slime-like properties, way back in the beginning chapters? Neither of them knew at the time, but this chemical composition neutralized the effects of Koro-sensei's antimatter body, reducing the odds of exploding to virtual nonexistence. In other words, from the moment he drank that, the threat of the Earth being destroyed was gone.
    • The wasabi and horseradish torture that Karma used on Grip in the Assassination Island arc later returns, with improvements, on one of the mercenaries guarding the mountain, in order to use his screams as bait to lure more mercenaries into a trap.
    • Koro-sensei's habit of grooming attackers at super speed? Extra Chapter 4 reveals it was part of his training in special surgery, which pays off there to heal and remove the tumor from a woman's brain, and in the final arc of the main story for saving Kaede.
  • Christmas in July: Invoked by Koro-sensei. No one in the class came by to visit or assassinate him during winter break after they learned about his past, so he decides to make up for lost time by having the class celebrate both Christmas and New Year's Day with him in February.
  • City with No Name: More like "Country" with No Name. Koro-Sensei was born in a poor and corrupt country that was very hard to live in. The name of said country was left ambiguous.
  • Clear Their Name: One arc has Koro-sensei framed for underwear theft and other especially perverted acts, causing most of his students' trust in him to dwindle. However, Karma catches on that while Koro-sensei is a pervert, he would never stoop this low, as losing his students' trust would be worse to him than dying. So Karma forms a small team (of himself, Kayano, Nagisa, Fuwa and Terasaka) to find the real culprit and clear Koro-sensei's name.
  • The Coats Are Off: Nagisa and Takaoka throw their jackets off before the final fight scene in Episode 22.
  • Combat Tentacles: Koro-sensei has them, of course. The cells that make up the tentacles can be transplanted onto a human, but they require an insane amount of energy to maintain and limit the recipient's human capabilities.
  • Continuity Cavalcade: Just about every minor character from previous mini-arcs (who wasn't a major Arc Villain) shows up at Class E's cafe at the school festival: the high school punks from the Kyoto field trip, old rivals from the main building, Yuuji and the assassins from the island hotel, and the old man and his daycare kids, to name a few.
  • Continuity Nod: Chapter 180.1 is explicitly stated to take place during Class 3-E's winter break — specifically, between Chapters 141-142, as Koro-sensei states to one of his would-be assassins that his students are busy "solving their homework" (i.e., meditating on what to do about Koro-sensei after learning of his Dark and Troubled Past).
  • Conveniently Timed Distraction: In Episode 7 of the anime, when a gang of high school delinquents corner Nagisa and his group in a street alley, Karma manages to fight off two of them but gets distracted when Kaede and Kanzaki are grabbed by the other members. This opening allows the gang leader to knock Karma out.
  • The Corpse Stops Here: Kayano finds a partially-transformed Koro-sensei kneeling over her sister's corpse, with Aguri's blood dripping off his tentacles, before he escapes.
  • Could Say It, But...: After being captured and detained by the government in order to stop them from interfering in their final assassination plan, Karasuma visits 3-E in order to berate them for trying to get to the mountain, detailing all the different defenses the mountain has and how skilled the mercenaries and their boss are, and leaves them telling them to cool their heads. Of course, his real intention was to give them vital information on said obstacles so they could make a plan and prepare to attack on the last day, when security was at its most lax.
  • Crippling Overspecialization:
    • One of the major challenges that every student (and assassin) must overcome is the penalty for failing to kill Koro-sensei: he will remember each plan, learn from it, and make sure he will never fall for the same trick twice. Fortunately, he has a hard time overcoming his weaknesses, which the students utilize to their advantage repeatedly.
    • This is also how Koro-sensei and Karasuma figure out that Takaoka is the mastermind behind the Assassination Island arc. The man is a soldier, not an assassin, and thus used the assassins under his employ as lookouts and guards instead of, you know, assassins.
  • Crossover:
  • Cruel Mercy: It's unclear whether Nagisa realizes this, but his finishing move against Takaoka counts as this. Even as it's happening, he knows that he'll never get Nagisa's smile out of his nightmares. It may have been kinder to just kill him.
    Nagisa: [sincerely, with a genuine smile] Takaoka-sensei, thank you very much.
  • Curb-Stomp Battle:
    • Akira Takaoka, elite soldier and special forces instructor, versus Nagisa Shiota, a 15-year-old kid with barely three months' worth of assassination training. Nagisa wins in under ten seconds because he treats it as an assassination, not a fight. He simply walks up to Takaoka, completely at ease until he's at point blank range and the only one prepared to actually attack.
    • In the final arc, Class 3-E goes up against a highly skilled team of mercenaries. They easily trounce everyone except the leader due to a combination of a Home Field Advantage, Karasuma's covert feedback, and training experience with Koro-sensei. As for their leader, he was overwhelmed with hit-and-run tactics designed to distract him from psyching himself up until he gets a Nagisa/Karma clap-and-kick takedown.
  • Curse Cut Short: When Yanagisawa and the Grim Reaper II arrive for the final battle, Terasaka lets out a "holy shi-" before being interrupted by Koro-sensei's Say My Name response.
  • Dancing Theme: Both of the anime's first season opening themes.
  • Death Course: The corridor that leads from the prison up to the floodgate control room is packed with a large variety of automatic traps and lethal hazards set up by the God of Death. To everyone's amazement, Karasuma maneuvers through the entire corridor with frightening ease.
  • Determinator: A Discussed Trope between Terasaka and Itona. Terasaka is of the opinion that it doesn't matter if you fail one hundred times if you finally succeed in the end, while Itona considers failure to be utter weakness until Terasaka gets through to him.
  • Depleted Phlebotinum Shells: Normal knives and bullets melt on contact with Koro-sensei, so the government developed a special substance that breaks down Koro-sensei's cells. The knives and ammunition used by the students are made entirely out of this substance.
  • Deus Exit Machina: During the Assassination Island arc, the students force Koro-sensei into his ultimate defense mode, in which he is rendered immobile for 24 hours. When Takaoka and his hitmen attack the class, the remaining 15 students and the other two teachers have to handle the situation by themselves.
  • Deus ex Machina: Averted. By the time Koro-sensei reverts back from his helpless ultimate defense mode at the end of the Assassination Island arc, everything is already over.
  • Detonation Moon: Koro-sensei's first major demonstration of power is to reduce the Moon into a permanent crescent by destroying 70% of its volume. Later it is revealed that the explosion was caused by a lab rat put in there by Koutarou Yanagisawa, the same scientist who turned him into what he is now as an experiment to test the effects of aging on antimatter cells, which went awry as the cells actually accelerated the aging and created a violent reaction upon the host's death.
  • Did You Just Flip Off Cthulhu?: In a verbal manner. In Chapter 3 / Season 1 Episode 2, in an attempt to look cool to his students, Koro-sensei pulls up the class tulips to replace their anti-sensei weapons with. However, it backfires, and as punishment, he was forced to replant the flower bed at regular speed, and later be the subject of an assassination rally with him dangling from a tree branch like a piñata while the students take shots at him.
  • Died on Their Birthday: Koro-sensei is killed in mercy by his students exactly one year to the day after he destroyed the Moon, on March 13th. This date is also his designated birthday, given that his actual date of birth is unknown.
  • Diegetic Soundtrack Usage: In Season 1 Episode 20, the second opening theme plays as the club's background music when Yuuji tries to impress the girls (and Nagisa in drag) with his dance moves.
  • Distant Finale: The epilogue takes place seven years after Class 3-E's graduation.
  • "Do It Yourself" Theme Tune: All four opening themes are sung in-character by Mai Fuchigami (Nagisa), Nobuhiko Okamoto (Karma), Aya Suzaki (Kayano), Ryōta Ōsaka (Isogai) and Shintarō Asanuma (Maehara) under the name "3-E Utatan". For Season 1 Episodes 7-8, the latter two are replaced by Yoshitaka Yamaya (Sugino), Sayuri Yahagi (Okuda) and Satomi Sato (Kanzaki) to mirror the events of the Kyoto field trip. At the end of Season 2 Episode 24, all the voice actors and actresses of Class 3-E perform "Tabidachi no Uta" ("Journeying Song") as their graduation theme, played during Koro-sensei's death and its tearful aftermath.
  • Do Wrong, Right: Koro-sensei welcomes the kids' attempts to kill him — but demands that, if they are going to carry out an attack, to at least be original and not cause problems for bystanders.
  • Doorstopper: What Koro-sensei produces every time he comes up with a "guidebook" for class excursions. One octopod's guide is another man's industrialized carbon-capture method—with indices, cross-references, info-panels, bullet points and plot-significance. They also make for very good improvised weapons.
  • Duel to the Death: The one-on-one knife duel between Takaoka and Nagisa at the climax of the Hotel Arc. Nagisa comes out on top, but despite previously wanting him dead, he opts to do the right thing and knock him unconscious instead—wearing the same placid smile that drove Takaoka off the deep end last time.
  • Dustbin School: The protagonists' class is where all the problem students are dumped so the other students can feel better about themselves and work hard to avoid going there. When they actually get better at school work, the school staff actively keeps them down and publicly humiliates them.
  • Dutch Angle: The panel where Nagisa's visible killing intent goes from 0 to 100 in an instant is drawn like this.
  • Dynamic Entry:
    • In his very first scene, Itona enters the classroom by casually walking straight through the back wall.
    • In Chapter 86, Karma comes out of nowhere and pulls off a two footed kick against Shiro's goons, while Maehara takes out another in the background of the same panel with a one footed version.
  • Early-Installment Weirdness: Threatening the world is one thing, but the first chapter ends with Koro-sensei threatening his students' families. The threat was made to counter the ideas certain students had that it was okay to bully other students into effectively becoming suicide bombers, and bonding and character development within the entire class have made that threat effectively non-existent. However, knowing Koro-sensei like we do now, it was an extreme action for him to take. Although perhaps, considering his backstory and what this post points out, it can be implied that he was just starting to get into his new identity.
  • Earn Your Happy Ending: Everyone in Class 3-E, plus Irina and Karasuma, get to go on to be happier, more confident people, each having found a fulfilling career and maintaining their friendships even years after graduation, showing they didn't undergo a year's worth of trouble (and several years' worth of bullying even before Koro-sensei showed up) for nothing. Even Koro-sensei earns his Bittersweet Ending; he does die, but he does so on his own terms, and he gets to reunite with Aguri, having spent a year honoring her last wish and leaving the world better than when he found it.
  • Easter Egg: In Chapter 2, on the newspaper page with the baseball player being attacked by Koro-sensei's tentacles, there's a side article captioned by the quote "My wife is a slut".
  • Elevator School: Kunugigaoka is one, but if you're in class E at the end of the second term, you don't get to advance.
  • Enemy Eats Your Lunch: Koro-sensei tends to overreact when the food he brings back from overseas winds up lost or stolen. In his introductory chapter, Karma baits Koro-sensei into a trap by stealing the gelato he bought from Italy and eating it in front of him during a quiz.
  • Enforced Plug: Parodied and lampshaded in the anime. When Fuwa tries to encourage her friends to buy the latest volume a certain Shonen Jump detective series, the scene cuts to a gigantic ad for Majin Tantei Nougami Neuro, Matsui's previous work, while a message encouraging the viewer to pick up the 12-volume compilation scrolls through the background. This does not go unnoticed by her friends.
    Kayano: That's nasty!
    Nagisa: Subtle product placement, Fuwa! Pay more attention to ethics in marketing!
  • Establishing Series Moment: The series' madcap humor, action, and absurdity are quickly established by the very first scene, where Class 3-E opens fire on Koro-sensei, who not only effortlessly dodges all their attacks, but casually continues doing roll call while doing so. We then learn about the "blowing up 70% of the moon" thing, just to cement how silly-but-violent this story can get.
  • Even Evil Has Standards:
    • Professional standards, no less. No assassin worth his salt would besmirch his name with the blood of innocent middle-school kids lest his name become an anathema, even if he loses some credibility in the process. This is enforced by a clause added to the bounty on Koro-sensei that says the bounty is worthless if any of the students are harmed.
    • In later chapters, Asano Jr. begins to believe that his father's teaching methods aren't right, and balks when his father, unsatisfied with Class 3-A's modest victory over Class 3-E at the school festival, suggests that he should have achieved an overwhelming victory by sabotaging their ramen restaurant and poisoning their food. As of the end of Chapter 118, he begins to see the monster his father truly is.
  • Everybody Cries: The ending features Class 3-E finally assassinating Koro-sensei. Nobody takes it well. Even Blood Knight Karma, Robot Girl Ritsu and Delinquent Terasaka couldn't stop themselves.
  • Everybody Knew Already: After his first match with Itona, Koro-sensei decides he has no choice but to reveal a shocking truth about himself: he is actually an artificially created creature. No one in the class is surprised since Koro-sensei already said he isn't an alien, and thus an artificial being was the only possible explanation left.
    Entire class: Well, duh. And?
    Koro-sensei: What a weak reaction! That was a pretty shocking thing to confess, wasn't it?!
  • Evolving Credits:
    • Irina appears in the "dancing" portion of Season 1's first opening sequence after her introduction in Season 1 Episode 4.
    • Season 1 Episode 7 follows Nagisa, Kayano, Karma, Sugino, Okuda and Kanzaki's group during the Kyoto field trip. The opening for that episode and the following one are sung in-character by their respective voice actors (see "Do It Yourself" Theme Tune above).
    • Ritsu can be seen near the end of Season 1's first opening theme, from Episode 7, despite not being formally introduced until Episode 9, and from Episode 10 on she appears throughout the opening.
    • Season 1 Episode 18 overhauls the second opening sequence with new images and animations of the characters in their summer uniforms as well as dancing on the beach in casual summer wear, highlighting the start of the summer break portion of the series.
    • Itona appears in the Season 2 opening from Episode 4 onwards after losing his tentacles and joining Class 3-E (specifically aligning himself with Terasaka's clique).
    • Following the "Reaper" arc, the Season 2's first opening from Episode 9 onwards showcases Irina's Good Costume Switch, and she and Karasuma are facing each other, signifying their growing bond. It also shows the Reaper's maskless face.
    • Season 2's second opening (Episode 15 onwards) changes per episode to show how many days the class has left to kill Koro-sensei.
    • All four ending themes usually end with a Koro-sensei smiley. For Season 2 Episode 24, however, this is replaced with an image of the class blackboard filled with messages from the students and Koro-sensei's congratulations to them for their graduation. This is also carried out into the opening credits for the final episode.
  • Exactly What I Aimed At: At the end of Class 3-E's battle against the marksman Gastro, Chiba takes the final shot, but it shoots right past Gastro instead of hitting him. Gastro mocks him for missing the shot, only for him to suddenly be crushed by falling stage lights, caused by Chiba's shot hitting the brackets.
  • Exact Words:
    • Used with Koro-sensei's teaching agreement with the government, which is not to harm any of the students.
      • Right in the beginning, after Terasaka nearly made Nagisa an anti-sensei suicide bomber, Koro-sensei warns them not to do something like this again, threatening them that just because he is banned from hurting them doesn't mean he's also banned from hurting their closest relations.
      • Because Ritsu, a military machine designed to assassinate Koro-sensei with the AI interface of a middle-school girl, is also enrolled as a student, Koro-sensei also has no recourse against her. He even points out that the government is exploiting a loophole in their agreement. However, it gets reversed when the class, fed up with her assassination attempts interrupting their lessons, retaliate via Terasaka duct taping her gun ports shut, as they can interfere. Koro-sensei then decides helping Ritsu go beyond her programming isn't "harm", exploiting it further in the class's and his favor.
    • Ritsu herself exploits this trope: after her creators discovered she's been upgraded by Koro-sensei, they decided to reset her back to her default settings, stating that everything not related to assassinating Koro-sensei must be deleted. However, Ritsu autonomously decided that the ability for empathy and friendship with the Class E students was absolutely vital for a successful assassination, and therefore non-removable.
    • Koro-sensei agrees to let the students shoot one tentacle for each of them that takes the top spot in the first term exams. Cue Terasaka, Muramatsu, Yoshida and Hazama taking the joint top spot in home economics (which is not in the primary five subjects accounted for by the school rankings), allowing them to make one shot each.
    • At the end of the Assassination Island arc, the class celebrates Nagisa defeating Takaoka, but were concerned that he didn't leave enough antidote to treat the sick students. Then, they're interrupted by the three hitmen he had hired, which said that they don't need no more antidote. Turns out they were telling the truth; Smog had poisoned the students with a milder toxin which will dissipate by itself in a few hours, instead of the more dangerous one Takaoka asks him to use.
    • Koro-sensei explains that he will blow up the Earth next March, and invites anyone to try and assassinate him. As it turns out, this isn't a mere threat; his antimatter body will involuntarily explode on March 13 of next year if he isn't killed by then.
  • Exclusive Clique Clubhouse: The academically under-achieving students are actually segregated to a tumbledown shack a long way from the main school building.
  • Explain, Explain... Oh, Crap!: Played for Laughs when Koro-sensei explains why he's using his once-a-month molting ability to get rid of his sunburnt skin... only to realize too late that it's only a few minutes before he's getting seven tentacles shot and all the kids are prepped to kill him.
  • Extremely Easy Exam: Inverted in Episode 5, where both classes 3-E and 3-A take exams in all the subjects. As class 3-E is treated like outcasts and isolated from the school's main building, the teachers of the main building up the difficulty of their tests by broadening their scope to cover all the subjects, which class 3-E's teacher Karasuma points out is unfair.
  • Failure Is the Only Option: The story will end as soon as someone successfully assassinates Koro-sensei. Of course none of the assassination attempts shown in the first hundred chapters or so are going to work.
  • Fastball Special: How Isogai launches Itona to the top of Class A's bo-taoshi pole. Using both hands and having exceptional high jump skills definitely helped.
  • Festival Episode: The day before the start of the second semester, Koro-sensei and some of the members of Class 3-E visit a festival to commemorate the end of summer. The kids, thanks to their training, turn out to be far too skilled at the game booths. Hayami and Chiba in particular end up being banned from the shooting range after practically robbing the stand of its prizes.
  • Flashback Echo:
    • When Koro-sensei notices a fragment of sizzling gunpowder from Nagisa's failed attempt, it triggers a cryptic flashback involving a burning laboratory, a mortally-wounded woman, and a humanoid monster cradling her in its arms. The woman is Aguri Yukimura, Class 3-E's previous homeroom teacher and Kayano's older sister.
    • When Itona reveals his tentacles, Koro-sensei becomes furious as he briefly recalls a tentacle piercing said woman's stomach. Aguri was killed by a tentacle container while trying to stop him from killing the scientists who performed the painful experiments that turned him into what he is today.
  • Fictional Sport: The students of Class 3-E play "assassination badminton" in PE class, which is actually more like volleyball in almost every way. The main differences are that they can only touch the ball with the blade of a wooden knife, and they use a tennis net instead of a badminton or volleyball net.
  • Fighter, Mage, Thief: There are two sets of this trope:
    • The three teachers: Karasuma physically stronger than the two others is the Fighter, laser-shooting Koro-sensei is the Mage and stealthy knife expert Irina is the Thief.
    • The three main students: Karma being the best unarmed combatant among the students (lampshaded by Karasuma) is the Fighter, Kaede who had during a time Combat Tentacles like Koro-Sensei is (or at least was) the Mage and Nagisa is the Thief being able to surprise his opponents with his unpredictable movements.
  • Final Exam Finale: The second term finals are literally this, though they aren't the end of the series. But it's The Final Question that properly fits the definition of the trope for Karma and Gakushuu. Aside from having proper Final Boss cred for being an insanely difficult math problem (when the internet got a hold of a translation of the question, the general consensus was that it was college-level geometry), Karma's solution involves him thinking through much of his Character Development over the course of the series. And for Gakushuu, his approach betrays his lack of growth over the series, and he fails to find the answer in time.
  • Five Rounds Rapid: Inverted. Irina's men favor using machine guns with the thought that no being could possibly survive that... not knowing that metals simply dissolve in Koro-sensei's body, which can only be harmed by weapons of a special material.
  • Flipping the Table: Invoked by Koro-sensei, who volunteers to coach his students for an upcoming baseball exhibition match. He brings along a miniature table stocked with food for the express purpose of flipping it over, thus achieving his dream of acting like one of those "hot-blooded coaches you find in sports series".
  • Foreshadowing:
    • Nagisa was built up to have a lot of hidden talent. Confirmed in Chapter 41, which reveals that Nagisa has an exceptional talent for assassination. To be specific, his ability to hide such bloodlust that it scares trained soldiers.
    • Nagisa's feminine appearance and talent for reading people are both noted quite early on. Then we learn that his insane mother invoked Dude Looks Like a Lady on him because she wanted a daughter instead, and that his talent for reading people comes from him having to predict her violent mood swings.
    • In Chapter 28, Koro-sensei takes several students to see an American superhero movie, wherein the major Plot Twist involves the Big Bad being revealed to be the heroine's brother. At the end of the chapter we meet Itona, Koro-sensei's Ax-Crazy "younger brother". Or, from another angle, despite being a main character Koro-sensei was built up to be the Big Bad, but its later revealed the true Big Bad is Shiro/Kotarō Yanagisawa. It's later revealed that Shiro was Aguri's fiance, making him Kayano's older brother-in-law.
    • Koro-sensei becomes furious when he sees Itona with tentacles. He was subjected to similar torture experiments by the exact same man.
    • In Chapter 67, Karasuma vaguely recognizes two of the mastermind's minions because he had seen them before in Takaoka's photographs of the soldiers he had previously trained, foreshadowing the mastermind's identity.
    • The Reaper is holding a rose and a bouquet of flowers when he's first described by Lovro. He first appears to the students of Class E as an unassuming flower salesman, offers Kanzaki a rose, and sells them a bouquet of flowers for Irina's birthday before the story reveals his identity.
    • In Chapter 90, Koro-sensei says that the only ikemens (hot guys) in the class are Isogai, and himself. Come Chapter 134, we see he was actually a fairly good-looking man.
    • Chapter 128 is one long flashback of all the hints throughout the previous chapters foreshadowing that Kayano has tentacles like Koro-sensei and Itona. For example, Shiro says that the "monster" in Class E averted their eyes as soon as they saw him.
  • Foregone Conclusion: The dramatic tension in the flashback to how Koro-sensei was transformed is in how everybody knows by that point how badly the growing bond between Koro-sensei and Aguri is going to end.
  • Formula-Breaking Episode: The assassination island arc breaks from the usual formula by having the class infiltrate a high security hotel and battle three professional assassins to save their friends.
  • Fractured Fairy Tale: Class 3-E's school play is a rendition of the legend of Momotarō done this way — courtesy of Kirara handling the screenplay.
  • Framing Device: The last compilation movie for the anime was framed as Karma and Nagisa, just the day before the Class 3-E reunion seven years after the main story, meeting up and talking to each other.
  • Freudian Trio: The main trio with Karma (hot-headed,assertive) and Nagisa (quiet,calm) who are respectively Id and Superego being a hair-based version of Red Oni, Blue Oni while Kaede is the neutral in their Power Trio. And then the teacher trio with Irina the Id (impulsive, a bit Womanchild as the youngest one), Karasuma is the Superego (task-oriented, disciplined, aloof) and Koro-Sensei being more balanced (goofy, playful but highly intelligent and serious as a teacher) is the Ego.
  • Freeze-Frame Bonus:
    • The kanji displayed at the back of the classroom changes as the episodes progress. The text reads, "Assassination", "Speed of Sound", and "Tentacle".
    • The "S.A.A.U.S.O." logo on the students' knives and weapons is a detail featured only in the anime. Pause at the right time and you'll find that it stands for "Special Arms Against Unidentified Slimy Octopus".
    • The English print in the newspaper article describing Koro-sensei's assault on a pro baseball game becomes ten times funnier in the anime.
      Article: encounter such a situation when I was pitching in a good condition. What the hell was it?" I am embarrassed since my teammates make fun of me, saying "JAPANESE HEITAI" and my wife gave me a meaningful comment, "I envy you". I had hard time a little bit to recover...
    • The "Poison Storage" manga in Episode 5 is pretty amusing, but it's easy to miss since it's only glanced over for a few seconds.
    • The second opening lists all the students' names in English, including a blink-and-you'll-miss-it shot of Kimura's real given name, "Justice", which isn't revealed until a few chapters later.
  • Fun with Acronyms: In the anime, the anti-Sensei weapons are labeled "S.A.A.U.S.O." which stands for "Special Arms Against Unidentified Slimy Octopus". In Japanese, it can mean "come now, [that's] a lie".

  • The Gambling Addict: One of The Chairman's first cruel acts on opening his school was to turn several students into hopeless gambling addicts as revenge for their bullying a student from his old cram school until he committed suicide.
  • Gender-Concealing Writing:
    • An important example that caught many translators off guard: When it is mentioned that there is someone in Class-E that has greater bloodlust than Itona, the lack of gendered language is used to mask that that person isn't Nagisa, but Kayano/Akari.
    • The brief discussion over Class E's previous teacher, Yukimura-sensei, was translated using male pronouns although the original uses gender neutral pronouns. Yukimura-sensei is eventually revealed to be a woman.
  • Gendered Outfit: When the students get their new, militaristic, "PE uniforms" at the end of volume 11, the boys' outfit is ordinary baggy combat gear, while the girls' is a cropped jacket and Lara Croft-style shorts over a skintight spandex unitard. Justified since Irina designed the girls' outfit (and it turns out that her preferred design was incredibly Stripperiffic, but she and Karasuma compromised).
  • Ghibli Hills: In contrast to the urbanized surroundings of the main building, the mountain where the Class 3-E building is located is an isolated outdoor paradise filled with all sorts of wildlife.
  • Genius Ditz: Futoshi in Extra Chapter 3. Even his friends are shocked at how much he knows about the legal system!
  • Gladiator Games: How final exams are depicted to the viewer. Armed with hammers, swords, magical staves, and ray guns, the students are thrown into a coliseum where they must slay a horde of gigantic, surreal monsters within a short time limit. In reality, they're just sitting in a chair, taking an exam on a piece of paper.
  • The Glasses Come Off: Deconstructed. One person uses this as a psychological trigger in order to fight better. Class E attacks him too quickly to even let him have a chance to do this.
  • Gondor Calls for Aid: During the school festival, Class E initially has trouble attracting enough customers to their ramen restaurant to compete with Class A. By taking advantage of their personal connections, the students manage to rack up a gigantic clientele, comprised of both total strangers and characters the students have previously met throughout the series, friend and foe alike (including some thought to have been killed off).
  • Gonk:
    • "Fake Ritsu" (the girl who impersonates Ritsu for exams and other public events) has heavy features and a warty nose.
    • The Loan Shark in the "Extra Class" story is incredibly repulsive-looking.
  • Goroawase Number: Koro-sensei is sometimes associated with the number 56 (which can be pronounced as "Ko-ro"). His baseball uniform has "56" on the back, and one Imagine Spot of Koro-sensei and Itona together has the former holding a board with "56" written on it. Also, in the same Imagine Spot, Itona holds a board with "1107" (1-10-7, "I-to-na") on it.
  • Gratuitous English: More like "Gratuitous IPA English". On the cover page of Chapter 55, the word assassination is rendered as əsˈæsənˌeɪʃən, which would actually be assassination, with the first "ass" as its own syllable. The correct rendering would be əˈsæs.ɪnˌeɪ.ʃən. Let this stand forever as the most pedantic entry on the page.
    • In a straighter example, after Class 3-E announce their finals grades (allowing them to shoot off seven of Koro-sensei's tentacles) and how they're going to factor their wager with 3-A into the deal, Koro-sensei is so shocked that he speaks a single word of English.
      Koro-sensei: What?
    • Amusingly, the English dub ended up preserving this joke... by having Koro-sensei speak Gratuitous Japanese instead.
      Koro-sensei: Nani?
  • The Guards Must Be Crazy: During the Assassination Island arc, Kimura managed to get two trained agents guarding one of the hotel floors to leave their spots and chase him, just by insulting them. Not to mention Kimura, a middle schooler, managed to outrun both of them.
  • Guilt-Tripping: Meg Kataoka is guilt-tripped by Kokona Tagawa into helping her study because the latter almost drowned in a swimming incident and blamed the former for it despite it happening because Kokona was the one being irresponsibly careless. It takes an intervention from Meg's friends and Koro-sensei to remove Kokona's emotional leverage over her.
  • Hands Go Down: When Isogai asks who in Class 3-E wants to volunteer for their plan to hijack a spacecraft bound for the ISS, almost everyone raises their hands despite being told that only two people could board. Koro-sensei then reminds everyone that the technology is still experimental. Instantly everyone's hands go down.
  • Happy Birthday to You!: Class 3-E celebrate the anniversary of the moon's explosion as Koro-sensei's birthday, so they get him a cake and sing Happy Birthday to him. Terasaka refuses to join in, claiming it to be "some bullshit", but is pinched into singing along by class representative Kataoka. They also sing the song in the English dub, which was released soon after the Happy Birthday song was deemed in the public domain, but that doesn't stop Terasaka from lampshading the trope:
    Terasaka: Dude, do we even have the rights to this song?
  • Hard Work Hardly Works: Played with. While Karma is the smartest and most naturally talented kid in class, not studying drops his rank from 4th in the school to 13th. Sure, 13th in an entire school without studying is no small feat, but everyone knows Karma can do better, especially himself.
    • Averted with Terasaka. He's not that bright and even he admits it, but by the end of the series has learned enough to allow him to do well enough on tests to get 46th place in the school and as he tells Itona, he learns from every failure. Sure he's still last in the class, but the improvement is still huge. He also works out a fairly complicated probability problem in his head when Principal Asano asks him to during his attempt to kill Koro-sensei with a challenge involving grenades in textbooks.
  • Hijacked by Ganon: The true mastermind of the Assassination Island arc turns out to be none other than Takaoka, having vowed revenge after Nagisa defeated him prior.
  • Hitman with a Heart: The "Extra Class" four-parter is about four assassins who decide to help out the owner of their favourite bar when they discover that she is having problems with a Loan Shark.
  • Hoist by His Own Petard:
    • During the baseball game between Class E and the Baseball Club, in the second inning the latter use the same batting strategy the former used in the first, so Class E uses the same defensive strategy the Club used in the second inning during the third — and the umpire cannot say anything, since he allowed it earlier.
    • Shiro suffers this when he injects himself with tentacle cells in order to directly combat Korosensei. This proves to be his downfall when he is knocked into an anti-sensei barrier and is nearly completely disintegrated.
  • Home Field Advantage: When up against a highly skilled mercenary team who earlier captured them in seconds. The tables are turned when Class 3-E has to break through them in order to get back to their classroom. Not only are they properly prepared and on the offensive this time, but the battlefield is the mountain their classroom is on, and they've spent the whole year getting to know every inch of the mountain like the back of their hands, and setting traps for Koro-sensei to now be repurposed against the mercenaries.
  • Homework Slave: Kataoka is a hardworking and intelligent student, making it very strange that she wound up in Class 3-E, where failures and delinquents are sent to isolate them from the rest of the student body. The manga reveals the reason is because her 'friend' forces Kataoka to act as her private tutor, to the point that she no longer has any time for her own work, causing her grades to slip and resulting in her being dropped in Class 3-E while the other girl remained on the main campus.
  • Hope Spot: After their return from space, Nagisa and Karma use the data provided by the astronauts from the International Space Station to learn that Koro-sensei is at far less risk than the mouse which destroyed the moon due to his sheer size, and has already taken a silicone solution earlier used which stacked on top of it, thus meaning that Koro-sensei's chances to explode on March 13th is barely minuscule. Too bad the government is not willing to risk the chance, and the students have to kill Koro-sensei anyways. At least Koro-sensei went out on his own terms.
  • A House Divided: The class turns into this at the start of the final term, with some wanting to try to find a way to save Koro-sensei's life and others preferring the security of coming up with a way to kill him, with Nagisa and Karma respectively leading the factions. Koro-sensei declares it will be settled with a game of paintball in order to prevent this trope from going too far.
  • Humans Are the Real Monsters: Aside from his stated desire to blow up the Earth, Koro-sensei does nothing bad within the scope of the series, more so as it is revealed that he is an involuntary walking time-bomb and wishes to be killed before he explodes. Humans, on the other hand, have more than proven themselves to be capable of being ruthless monsters, including experimenting on him when he was still a human, which turned him into the creature he is today after his augmentations went berserk.
  • Identical Stranger: Hotaru, the narrator of Chapter 180.1 and daughter of the owner of a diner Koro-sensei frequents, looks like Nagisa if he had longer hair and was actually a girl.
  • Idiosyncratic Cover Art: Every manga volume features Koro-sensei's face, the color and emotion varying across each one.
  • Idiosyncratic Episode Naming: All of the chapter and episode titles have the word "time" in them. This can be interpreted as a reminder that Class 3-E only has a whole year to kill Koro-sensei before he blows up Earth, as well as an alternate reading on "class period" (some chapters even have the exact same title as a previous chapter with the phrase "2nd Hour" added to the end of it, befitting with the series' school theme).
  • Inconsistent Spelling: It took a while for the official readings for everyone's names to come out.
    • Meg Kataoka's first name used to be spelled "Megu" pretty often, as seen in translations and the anime's second opening theme.
    • Korosensei, Koro Sensei, or Koro-Sensei? Most official translations use "Koro Sensei", but opinions still differ.
  • Indignant Slap: The students of Class 3-E try doing parkour without a sense of awareness for their surroundings, and accidentally injure an innocent old man. For this, the entire class is brought out to be slapped across the face, the only time in the entire series when Korosensei breaks his rule against harming his students.
  • Insert Song: "Moonlight" (月光) in Season 2 Episode 16 of the anime.
  • Interquel: The novel sections included in the "Korotan" series of educational reference books are midquels that take place over the course of the students' year in Class E. The exception to this is the story in "Korotan D" which is regarded as canon and takes place in the gap after Class E graduates middle school but before the epilogue.
  • Invisible Parents: Though they may be briefly mentioned on occasion, the students' parents never appear until dozens of chapters later, if at all.
    • Chiba and Hayami's parents are shown in a flashback, respectively.
    • Nagisa's father, who is often absent due to his work, appears in Chapter 76. He seems to be nice, and it's mentioned that Nagisa's mother is strict. Chapter 112 reveals that "strict" is a severe understatement.
    • Takebayashi's parents (Chapters 78 and 79) aren't happy with his poor grades and are shown to be quite distant from him at home and because of that, he leaves Class E for a couple of chapters.
    • Kimura's parents and Kirara's mom are shown in a flashback in Chapter 89.
  • Japanese Ranguage: Used a lot with regards to Irina Jelavic, a Serbian assassin who teaches English for Class 3-E.
    • During her introductory arc, Class-E makes a half-baked attempt at shortening "Jelavic-Oneesama" to "Vic-Neesan". Their inability to pronounce the "v" properly, compounded by Irina's unpleasant personality, earns her the nickname "Bitch-neesan" (later "Bitch-sensei", when she wins their favor) for the rest of the series.
    • Later Invoked by Irina, who as the language teacher spends an entire lesson trying to get the students to avert this.
  • Jerkass: Almost EVERYONE who isn't in Class E, and a few students who are until Character Development. The school's chairman gets special mention, because he specially designed the school to encourage its students and teachers to be this way to everyone associated with Class E. Seriously, if this weren't a manga, a good half of this school's faculty would have been canned long ago in any country with a reasonable education system.
  • Kansas City Shuffle: During the island assassination attempt, Koro-sensei uses his keen sense of smell to deduce that Chiba and Hayami, the class' best snipers, plan to deliver the killing blow from a nearby mountain. What he detected were dummies set up by the students to lure his attention away from the snipers' true hiding spot underneath the ocean.
  • Kill Sat: Chapter 161 / Season 2 Episode 21 has the government use one in an attempt to kill Koro-sensei. It shoots a powerful laser that is dangerous to Koro-sensei but otherwise harmless to the school building he is in.
  • Kill the Ones You Love: At the end of Chapter 177, Class 3-E finally kills Koro-sensei at his behest after defeating Shiro and the second Reaper, with Nagisa dealing the fatal stab while the rest pin him down. However, by that time the students had already grown close to him, who had shown them the love and care their previous homeroom teachers denied them, as well as helped them to gain confidence and develop intellectually, physically and emotionally, so understandably all of them broke down crying over what they had done.
  • Kiss of Death: Downplayed. In this universe, a sufficiently potent but otherwise mundane kiss can render someone paralyzed or unconscious. Irina uses this on Nagisa to assert dominance over the class early on. Nagisa later uses the technique he learned from her to calm down a rampaging Kayano.
  • Kneel Before Zod: In the island arc, Takaoka forces Nagisa to apologize for beating him in Takaoka's first arc, to save the lives of his comrades.
  • Kryptonite Is Everywhere: Invoked. The anti-sensei material is cheap and easy to produce in large amounts, so Class 3-E and all the other would-be assassins introduce it to Sensei's life as much as possible in all forms, from bullets and knives to pudding and henna tattoos.
  • Laser-Guided Karma: Whenever the higher-ranked students are shown to look down upon or make fun of Class E students, Koro-sensei helps them to get their revenge or something eventually happens to make them regret it, unless Asano Sr. intervenes. In the end, Shiro/Yanagisawa, the Mad Scientist who was behind most of the misfortune in the series, is left a vegetable while his antimatter experiments are officially outlawed, while Asano Sr. is forced to resign after his school's discriminatory policies are leaked into the public.
  • Laughing Mad:
  • Leaning on the Fourth Wall: Throughout the first day of the island vacation, the students wear casual street clothes instead of their typical school uniforms. In Chapter 73, the following day, they're already back in their P.E. jerseys.
    Kimura: Well, there aren't any other guests, and these are comfortable.
    Fuwa: And it would be cruel to have to think up clothes for a second day.note 
  • A Lesson in Defeat: The first term's final exams are treated as this for Karma, who slacked off from studying and saw his grades slip compared to the midterms, and Asano Jr. who, along with his clique, lost several "best in grade" positions to Class 3-E in the second semester finals, which Karma ultimately aced.
    Koro-sensei: For those with a high level of aptitude... the sooner they know the frustration of defeat, the greater their growth will be.
  • Letting the Air out of the Band: Done several times throughout the anime for comedic effect. For example, in Season 1 Episode 2, gentle music accompanies the touching moment where Koro-sensei declares his dedication to his students. It quickly dies when Nagisa complains about the weird extra credit question on his notebook.
  • Loophole Abuse:
    • Koro-sensei promises a free shot at one of his tentacles to anyone who can earn the top score on one of the subjects tested on the first final exam. Although three students earn a high score on a subject exam, Koro-sensei only starts to panic when four more earn perfect scores on Home Economics, which he completely forgot about because it's generally not considered one of the five main subjects.
    • As lampshaded by Koro-sensei, the government used one to enlist Ritsu into the class. By giving a killing machine an AI and virtual face based on a teenage girl, they were able to register it as a student, and thus unable to be harmed by Koro-sensei.
    • Ritsu herself exploited the trope when her creators reset her. The procedure removed all of Koro-sensei's upgrades which were deemed unnecessary for assassination, but Ritsu autonomously decided that the ability for empathy and friendship with the rest of Class E was vital for a successful assassination, and thus non-removable.
  • Logical Weakness: Assassination skills are for getting the drop on a target, not prolonged conflict, making most assassins far less effective at combat than their general competence level would suggest. Infiltration-style assassins like Irina lose most of their effectiveness once their cover is blown.
  • Lost in Translation: The series uses a lot of puns that are really hard to translate, so lengthy translator notes have to be included with every chapter.

  • Marshmallow Hell: Invoked by Irina. When Nagisa refuses to give her his notes on Koro-sensei after helping her earlier (because he already gave her all his current info) she reels him in and threatens to suffocate him.
    Nagisa: Stop it, Professor Bitch! I can't breathe over your enormous tatas!
  • Masculine, Feminine, Androgyne Trio: The main student trio is made up of the masculine Karma, the feminine Kaede, and the androgynous Nagisa.
  • Masquerade: Aside from Asano Sr., the rest of the school (and the world) has no idea that Class 3-E is harboring the culprit who blew up the moon, and the ongoing attempt at his assassination is a total secret. It's been stated that the government is willing to wipe the memories of anyone unable to uphold this secret.
    • When the students accidentally injure an old man while trying out their free running skills in a public area, Karasuma, Koro-sensei, and the students end up going to a lot of trouble compensating for his work as a cram school teacher which he misses while recovering in the hospital, thus preventing him from leaking their secret.
    • Played for Laughs when Yuuji notices a large number of sketchy looking customers (Lovro, Red Eye, Gastro, Smog and Grip) at Class 3-E's school festival cafe. Nagisa tries to come up with increasingly ridiculous excuses to hide the fact that they're all professional hitmen.
      Yuuji: Why does [Red Eye] have a gun? Maybe we should call the police...
      Nagisa: WAIT! He's...Y-Yoshioka-san from the local hunting club.
      Yuuji: "Yoshioka-san"? He doesn't look like a Japanese guy!
      Nagisa: H-he changed his name because he likes Japanese anime so much...
  • Meaningful Echo:
    • After Koro-sensei gets himself into a tangle after failing to solve a wire puzzle in less than a second, Asano Sr. taunts him that not every problem can be solved with speed. Later, Koro-sensei repeats this line to his students after revealing the mountainside pool he built by damming a stream and letting it pool up overnight.
    • Karasuma's first words to the students, in regards to Koro-sensei: "I'll cut right to the point. I want you to kill this monster!". Later repeated to Class E (in a metaphorical sense) by Asano Jr., who is fed up with the Chairman's educational methods and wants them to take him down during the second semester final exams.
  • Meaningful Name: "Assassination Classroom," at first, is what it appears to be: a special class of students tasked with assassinating a person. Only the person who they're actually trying to kill is a master assassin himself. So it's a bunch of students assigned to kill a dude who is skilled at killing dudes who wants and teaches the students to kill him.
  • Medium Awareness: In at least one dubnote , Koro-sensei often comments on the soundtrack and other scene setting techniques.
  • Minimalistic Cover Art: The manga volume cover artworks usually consist of nothing more than a few solid colors and Koro-sensei's face. Special mention goes to the Volume 5 cover, which shows Koro-sensei's poker face: blank white with the ._. emote. Generally speaking, the odd-numbered volumes will have simpler cover arts than their even-numbered counterparts.
  • "Miss X" Pun. Invoked. The students nickname the professor "Korosensei" as a pun on "Korosenai", meaning "Cannot be killed", and "Sensei", the Japanese Honorifics for a teacher.
  • Monster of the Week: Inverted. Koro-sensei is the Villain Protagonist of the assassination side of the plot, and in each story he foils an assassination attempt made by a different student, teacher, or character from outside the classroom.
  • Mood Whiplash: The series' silly, comedic tone can swerve into a much darker one when you least expect it to. Taken up a notch in the anime adaptation, which makes even the minor silly and dramatic moments contrast each other to a greater degree than their manga counterparts.
    • Chapter 60 changes things up a bit when a fun and interesting day at the beach ends with a couple of students suddenly collapsing onto the floor and coughing up blood.
    • Chapter 75, which features the class' attempt at shipping Irina with Karasuma, fluctuates from hilarious to tragic, and back again.
    • Chapter 83 is a comedy chapter about Koro-Sensei being framed as a Panty Thief. Then it turns out to be a set-up for Shiro and Itona making another elaborate and dramatic attempt to kill Koro-Sensei, which ends with Shiro dismissing Itona when he fails to do the job and leaving him to die.
    • Chapter 98 has the main cast showing Koro-Sensei their newly-acquired equipment, skills and resolve (while ruining his relaxation time, but he doesn't mind). Meanwhile, the God of Death kills Red Eye, and Irina is next on his list.
    • The light-hearted Valentine's Day arc and the subsequent chapters are followed by the government stepping in and executing their final plan to end Koro-sensei's life once and for all.
    • An in-universe example after Korosensei's death, immediately after the spoilered event, Class E enters their classroom and finds that Koro-sensei left them each a ridiculously oversized scrapbook/guidebook. By the time that morning comes, the entire class is too tired out by both the length and Korosensei's commentary to be sad anymore.
  • More Dakka: The "spray and pray" method was an early but hopeless tactic used by Class E against Koro-sensei. More creative uses of this strategy are eventually utilized, such as aiming the hail of gunfire indirectly at him to reduce his concentration, aiming around him to limit his escape routes, or aiming it at a hostage, since his ability to defend others with his mach speed is relatively lackluster.
  • More than Just a Teacher: Korosensei is a bizarre hyperintelligent octopus-like creature who has threatened to destroy the world. Until then though, he's decided he wants to work as a high school teacher
  • Morton's Fork: How Takaoka tries to crush Karasuma's reputation as a teacher. Karasuma has the option to either send one of his under-trained pupils into a hopeless knife duel against Takaoka, or refuse the challenge and let Takaoka remain as Class E's new barbaric P.E. teacher.
  • Motor Mouth: Koro-sensei's narration of the previews is as rapid as you might expect, and not entirely germane to what's actually going to happen.
  • Mundane Made Awesome: The extensive use of visual metaphors does a fine job of making ordinary actions come to life.
    • Exam questions are depicted as bizarre, gigantic monsters which the students need to conquer or slay. In the first midterms, they're just Dire Beasts. In the first finals, they've become armored giants, tanks and such. By the second finals, they've gone all the way to Eldritch Abominations. The kids are armed not with writing utensils, but with knives, hammers, swords, and staves. Taking a test has never been so epic.
    • One chapter manages to visually equate the act of clapping in front of someone's face to ruin their concentration to a nuclear explosion in a city.
    • Played for Laughs after the students discover an incredibly valuable mushroom (a completely ordinary matsutake) while scavenging their mountain for foodstuffs. It emits a glorious light that's painful to look at and a dramatic wind that manages to blow one of the students away.
  • Mundane Utility:
    • Koro-sensei does this a lot. He uses his super speed to clean the schoolyard, give one-on-one coaching to all the students simultaneously, get snow cone ice from the North Pole, and so on. He also disguises himself as a baseball and uses his color changing abilities to give his team instructions without the other team noticing.
    • The students will sometimes use their assassination skills for mundane tasks, such as winning at every booth during a festival.
  • Myth Arc: Though the plot's objective (kill Koro-sensei and save the world) is spelled out from the get-go, the story is divided into several short, episodic arcs that can stand alone like the ones found in a typical slice-of-life manga. However, there's enough foreshadowing, continuity, and other little details to tie them all together and consistently hint at a greater, overlying mystery which is ultimately revealed in the last quarter of the series.
  • Mythology Gag: In Chapter 178, one of Koro-sensei's advices to Fuwa that he wrote in her personalized guidebook is for her to write a spinoff story where he's a demon king. This alludes to the spinoff Koro-Sensei Quest!, which debuted a year prior to the chapter's release.
  • Never Recycle Your Schemes: Justified. Once Koro-sensei knows how to defeat a tactic, he's smart enough and aware enough that it will never have a chance of working on him again.
  • Nightmare Face:
    • A Running Gag with Hazama is that she's very good at scaring the crap out of people, including Koro-sensei, and loves doing it.
    • Koro-sensei himself becomes a lot more terrifying when he breaks out his Game Face due to extreme anger.
    • As a general rule, the manga also loves to give certain characters metaphorical nightmare faces when their evil intentions come up front, like Chairman Asano or Nagisa's mother. The results are suitably terrifying.
  • No Endor Holocaust: Korosensei blows up most of the Moon. This does not affect life on Earth in any way. Tidal patterns continue normally as well. It is ultimately a downplayed example, as a newspaper early on mentions the problems come from the moon and in the finale things finally begin to settle as the moon collapses and become closer to Earth, eventually making the Earth's system returns to normal.
  • Non-Standard Character Design: Koro-sensei and Asano Sr. both look quite distinct from any other character. Most characters are your basic anime designs, drawn with rounded lines and uneven hair. It goes without saying that Koro-sensei, being a tentacle monster, has a unique entirely rounded appearance. Asano Sr. is more subtly strange, but his design also feels off compared to (other) humans. He is incredibly angular and sharp-looking, and his clothes have noticeably fewer creases and wrinkles. The contrast between the two is probably intentional, to match their opposing roles in the story.
  • No-Sell: Irina lures Koro-sensei into a shed where he's bombarded by hundreds of rounds of machine gun fire courtesy of her henchmen. Instead of dodging, he allows them to fire away to prove that lead bullets, unlike the anti-sensei ammo that they chose not to use, will simply dissolve on contact with his body.
  • Not So Extinct: The Japanese river otter, declared extinct in 2012, appears in Chapters 56 and 88.
  • Not-So-Forgotten Birthday: Due to the events of the athletic festival and the second mid-term exams, the students forget about Irina's birthday. To make it up to her, they secretly arrange for Karasuma to present her with a birthday gift. The plan backfires thanks to Karasuma's blunt insensitivity towards her feelings, setting the stage for the Reaper to manipulate her into betraying the class.
  • Offstage Villainy: Aside from his shameless perversion, Koro-sensei has not done anything that is morally wrong on-screen. And yet, he has all but destroyed the Moon in the backstory and will do the same to the Earth in the close future. No info is provided on whether he massacred the combined armies of the world trying to kill him or just did a No-Sell of their barrage. This is later subverted with the reveal that he didn't destroy the moon nor does he want to destroy the Earth; a massive explosion is simply what happens when the bodies of antimatter-infused creatures like Koro-sensei undergo critical failure. The plot started as a variation of Suicide by Cop combined with upholding the last wish of his love.
    • On the other hand, we find out that Koro-sensei used to be an assassin, no less than the previous Reaper, and thus he's responsible both for countless victims killed for a price and for training the current Reaper, who eventually turns against him. It's only after being transformed and losing his loved one that he takes a turn for the better.
  • Oh, Crap!: Standard reaction for anyone who is subject to Nagisa's superbly hidden bloodlust and talents for efficient, ruthless assassination. Notable in that two highly skilled government field agents are the ones most prominently displaying massive "Oh Crap" faces after they realize what's happened.
  • Once More, with Clarity: When Akari/Kayano first saw Koro-sensei, she only saw a monster apparently playing with her dead sister's blood. When we see what happened from Koro-sensei's perspective, he was actually swearing an oath on her blood to watch over Class 3-E in her place.
  • One-Hit Kill: Lovro's "secret killing technique" is designed to turn the tide of a battle between a skilled combatant and an assassin to the latter's favor. It's extremely effective, but only works under very specific conditions. He teaches it to Nagisa, who eventually uses it to defeat Takaoka during their rematch at the climax of the Assassination Island arc. And when the Reaper demonstrates his advanced version of the technique, it's revealed that pulling it off at just the right moment will paralyze the opponent for a few minutes. It's appropriately dubbed the "clap stunner".
  • Opposites Attract: Eventually Karasuma and Irina. They're a Hair-Contrast Duo as Karasuma fits the seduction-proof and aloof Tall, Dark, and Handsome persona while Dude Magnet Irina is a living example of Everyone Loves Blondes being approachable and flirtatious.
  • Our Monsters Are Weird: The "monster" representing the Social Studies exam is a metallic, six-limbed humanoid with a gun turret for a head. Its "evolved" form, which appears during the second Final exam, is twice as big, walks on ten arms, and is armed with a ridiculous number of firearms.
  • Paintball Episode: Chapters 142-149 (Season 2 Episode 17-18 of the anime) has the entire class engage in a paintball civil war to settle the dispute on whether they want to kill or save Koro-sensei.
  • Palatial Sandcastle: When Mr. Karasuma puts Koro-sensei in "time-out" in a sandbox, he uses his Super-Speed to build a perfect replica of Osaka Castle out of sand.
  • Le Parkour: After all their physical training in the first term, in second term class E starts training in freerunning. They use it in an extreme version of Cops and Robbers against Karasuma and Koro-sensei.
  • Pit Trap: The Reaper uses one against Koro-sensei, causing him to fall into the same cell that Class 3-E is locked in. Inspired, Kayano later built one filled with Anti-Sensei bullets hidden inside the school's storage shed, which she uses along with her tentacles to try killing Koro-sensei, although Koro-sensei manages to escape this time around by firing an energy blast into the side wall and then digging his way out.
  • Post-Kiss Catatonia: Used as a plot point: To stop Kayano's tentacle-induced rampage, Nagisa goes and delivers a 15-hit kiss to knock her out, so Koro-sensei can remove her tentacles.
  • Pragmatic Villainy: When Takaoka is trying to get his revenge he hires three assassins and sends them after class E. They all fail, of course, though it turns out to be because they weren't really trying at all. Afterward, they point out that killing a bunch of kids just because some nutjob wants them to would generate too much unwanted attention and legal trouble to make it nearly worth the amount they were being paid.
  • Pre-Asskicking One-Liner: The showdown between Karasuma and the Reaper begins with a line that is both badass and completely encapsulates the tone of the series as well as Karasuma's character...
    Karasuma: You're a bad example to the students. I'm going to have to ask you to leave the classroom.
  • Precision F-Strike: Used in the English dub (albeit censored) during the opening for Season 1 Episode 17, when Kunudon finds out that Class E gets to go on the exclusive school vacation.
  • Pretty Little Headshots: Averted, as much as is possible for a manga aimed at this age group. When the Reaper recalls making a kill by firing between two Shinkansen lines going in opposite directions, we see his victim from the exit wound side of his head, with a very large spray of blood.
  • Professional Killer: The students of the titular Assassination Classroom are mere middle school students with no prior experience in the killing arts. They have only one target: Koro-sensei, their nigh-invulnerable homeroom teacher who's hell-bent on destroying the world at the end of the year. Irina, a professional Honey Trap assassin, becomes the students' foreign language teacher after her initial attempt on Koro-sensei's life fails miserably.
    • While the Assassination Classroom increasingly become better in assassinations, none of the students are actual professional assassins and never become as such. The series introduces several actual professional assassins who are much more skilled than the class, with each of them having particular quirks. The only reason why they far worse than Class 3-E is because they are too unfamiliar with Koro-sensei and lack combined teamwork of 28 people to do the job right.
    • Among all professional assassins, the best is the legendary assassin nicknamed God of Death, who has ever successfully killed their target. While the God of Death introduced in the series failed to kill any of his targets on-screen (as the first two are revealed to be alive), it turns out that he was merely the apprentice of the first God of Death and stole his title after betraying him. The original God of Death was none other than Koro-sensei in his human life.
  • Psycho Serum: Side effects of having tentacles transplanted into your head include pain, violent meltdowns, reduced intelligence, and single-minded tenacity. When Itona finally has his tentacles removed, the lack of these side effects makes him act like a completely different person.
  • Public Domain Soundtrack:
    • During the Island arc, Irina plays Chopin's "Fantaisie-Impromptu" on the piano to distract the hotel guards so that the students can get past.
    • The Episode 0 OVA has Franz Schubert's Ave Maria playing in the opening and end credits.
  • Pun: Tons, most of which incorporate "殺", the kanji for "kill".
  • Punch a Wall: Parodied. After being insulted by Karma, Korosensei tries to let his frustrations out by punching the class wall; however, as Nagisa notes, he punches like a wet sponge.
  • Race Against the Clock: On March 13th of the next year, Koro-sensei plans to blow up the Earth. The students, along with the handful of people aware of the threat, only have a year to kill him.
  • "The Reason You Suck" Speech: Weaponized by Class 3-E in the island arc, when they force Koro-Sensei to watch a secret-camera video compilation of all his sleazier, more dishonest and more embarrassing activities to soften him up.
  • Reassignment Backfire: Asano Sr. set up Class 3-E as an example to students on what will happen to them if they don't excel in their studies, while encouraging other students to bully them. This backfires after Koro-sensei comes in and starts improving their grades and morale. Though the other classes initially don't notice this growth, attempts by the two Asanos to beat Class 3-E back down only make the other classes respect the growth they make. Come the second semester finals, when Class 3-A finds themselves beaten by Class 3-E into the high spots of the Top 50, Asano Sr. finds that the students of Class 3-A would almost welcome going to 3-E in order to improve, while simultaneously stating that the Chairman's teaching method doesn't work. Suffice it to say, the Chairman does not approve of these developments.
  • Reel Torture: In the Assassination Island arc, the class forces Koro-Sensei to watch a recording of him reading adult magazines. They do this in hopes of demoralizing him so that their planned assassination attempt will be easier.
  • Refuge in Audacity: The "secret killing technique" is essentially fueled by this trope. The first step is to do something completely insane to get the enemy's attention (like dropping your weapon). The second is to completely ruin the enemy's concentration by clapping. The reasoning is that doing this buys you enough time to change a battle of attrition (soldier) into a surprise attack (assassin).
  • Reveal Shot: After Karasuma sees a happy group photo of Takaoka with his JSDF students, he then finds a photo from the reverse angle, which shows that the students have their hands tied behind them and welts and scars all over their backs.
  • Rewatch Bonus: Koro-sensei's actions throughout the series all take on a very different bent once you know his backstory and motivations, especially that he wants the students to succeed in killing him.
  • Rooftop Confrontation: The final showdown with Takaoka in the Assassination Island arc takes place on the helipad of the hotel.
  • Running Gag:
    • Discovering or displaying Koro-sensei's weaknesses.
    • Koro-sensei's poor disguises.
    • Koro-sensei being tricked by his students into comedic situations.
    • Poking fun at Nagisa's androgynous appearance.
    • Kayano's hatred for big boobs as well as her lack of chest.
    • Karma's tube of wasabi.
    • Terasaka's lack of book smarts compared to the rest of the class.
    • Irina's failed attempts at Fanservice.
    • Whenever Koro-sensei and the class have a "sinister" plan at the end of a chapter, everyone makes the same Nightmare Face, with a single student as an exception. This also applies to other kinds of group faces, and in both cases the student with the different face is usually (but not always) Nagisa, who instead either has a meek smile or bored look.
  • Russian Roulette: After Chairman Asano's Villainous Breakdown, he challenges Koro-sensei to a variation on the trope involving handbooks and grenades, with Koro-sensei's place in the school being at stake.

  • Save Our Students:
    • Koro-sensei is at Kunugigaoka Middle School to help their lowest-performing students excel... through a liberal application of superpowers and some rather unusual extracurricular activities.
    • Subverted occasionally. He's not the end-all for their grades, as shown when Karma drops several points in the first round of finals despite Koro-sensei's efforts because he didn't care enough to study. Koro-sensei also learned after the first midterms that he needed to set more reasonable goals for his students than he previously had.
  • Scare 'Em Straight: Parodied. Koro-sensei draws a short comic that is presented as if it were this to Kataoka to warn her that she may grow up to be dangerously codependent if she does not learn to stand up for her own needs more. It's much funnier in the manga than how it is described here.
  • Scary Symbolic Shapeshifting:
    • Karma is known for being a terrifying Sociopathic Hero and Bully Hunter with a liking for violence. He's occasionally portrayed as having Hellish Pupils when he's angry and characters frequently imagine him having demon horns or a tail.
    • Played with. Nagisa is actually a pretty decent guy, but can be quite terrifying due to his talent for assassination and bloodlust. Often when characters sense his killing intent or become afraid of him, he's seen as a snake or reptilian monster.
  • Screen Shake: The anime simulates this effect in several scenes, particularly when Koro-sensei is showing off his power. In the scene when he makes the tornado, the camera seems to move around as if being buffeted by wind.
  • Screw the Rules, They're Not Real!: Given the students are underdogs with below-par resources, they resort to breaking the rules frequently.
    • In the first episode, Korosensei threatens to harm his students' families and loved ones if they ever do something reckless like suicide bombing ever again, as nothing protects them from him.
    • Subverted early on when Nagisa fears Korosensei is trying to kill Sugino, since despite having an agreement with the government not to harm the students, there's nothing and no one who can stop him from just breaking the rules. Luckily, Korosensei turns out to have been analyzing Sugino, not performing murder.
    • During the pole toppling event, Class E is up against Class A, and must win or Asano will get Isogai expelled for having a job. Unfortunately Class A has a massive advantage in numbers and several well-built exchange students, so Isogai has his team defy every rule not directly stated in the rule book- using their own pole as a weapon, playing dead and charging into the stands. In the end, their unorthodox methods beat Asano's careful strategy.
    • Karma goes up against Grip for a fist fight. However, despite claiming they both want to fight with their hands, neither play fairly and both use Smog's gas, though Karma wins as he predicted Grip would use underhanded methods and surprises him with his own canister of poison.
    • During a game of cops and robbers, rather than try to sneak past Korosensei to get to the jail and free their classmates, the students simply bribe him into letting them go. Karasuma is not pleased.
    • While playing baseball, Class A decides to all stand in the infield which shouldn't fly, but the umpire happens to be on their side and doesn't call them on it. Class E then realizes the rules don't really matter at this point and utilizes intimidation tactics by standing a few feet away from the batter.
    • Korosensei himself, aside from the whole "destroy the planet in a year" thing, does not kill or significantly injure anyone, at least onscreen. Other assassins have no such restrictions, so they often take advantage of Korosensei's inability to retaliate by mercilessly abusing his desire to protect his students.
  • Self-Mutilation Demonstration: When the students doubt the effectiveness of their guns' anti-sensei bullets, Koro-sensei takes a gun and shoots one of his own tentacles off to prove that he had in fact dodged the entire class' barrage of fire; the tentacle fully regenerates itself a few seconds later. He later repeats it when showing the students how lost tentacles restrict his movement speed.
  • Sexily Modest: When Bitch-Sensei undergoes a Good Costume Switch, swapping out of short-skirt and cleavage-baring top for a modest sweater and Proper Tights with a Skirt. The male students actually find her far more attractive afterwards for doing so.
  • "Shaggy Dog" Story: A mysterious person infects Class 3-E with a virus that will eventually lead to a slow and agonizing death. Instead of handing over the helpless, immobile Koro-sensei in exchange for the antidote, the teachers and students who have not yet succumbed to the virus spend an entire arc infiltrating a dangerous hotel full of bodyguards, assassins, and spoiled brats in order to steal it from the mastermind. The mastermind, who turns out to be a vengeful Takaoka, renders all of their efforts pointless by blowing up the antidote in front of the class. Subverted when it's revealed that Takaoka's assassins, who weren't nearly as sadistic and unprofessional as their boss, secretly swapped the lethal virus with a harmless stomach bug.
  • Shipper on Deck / The Match Maker: Everyone in the class is rooting for Karasuma/Irina and even actively tries to get them together especially in the first episode of season 2. With the exception of Kurahashi, who has a crush on the former and can be seen crying in the background whenever they make progress.
    • Karma and Nakamura are this toward Kayano and Nagisa.
  • Shout-Out: The series has so many shout-outs to current events, video games, and manga that it needed its own page.
  • Show Within a Show: The Sonic Ninja movies. Takebayashi is also mentioned to like an anime called The Reason My Sister Became a Hiroshima Fan Must Be Because of the Influence of Her Boyfriend which had an actual theme song composed for it in the anime. In "Korotan D," there's a film adaptation of a novel called Gold City.
  • Shown Their Work:
    • The BB guns and the live ammo weapons used in the series are based off of real-world firearms. Both the manga and the anime pay very close attention to details to both the artwork and the animation.
    • The covers of Shonen Jump seen in the anime are drawn to look exactly like those seen in recent issues. Episode 0 and Episode 11 feature Ryotsunote  and Usoppnote , respectively.
    • The technique Lovro taught Nagisa basically amounts to clapping in a heated battle. The point is to disrupt the enemy's concentration for a moment through the noise as they would not expect such a move, and leave him open for another sneak attack. The Reaper developed this further, not only disrupting concentration, but utterly shattering the psyche. This technique seems silly yet effective at first, but is actually based on a real sumo technique known as nekodamashi, which operates upon the same principle: temporarily break the enemy's concentration to create an opening.
  • Shut Up, Hannibal!: During the final battle against Yanagisawa and the Reaper 2.0, the former repeatedly ordered the Reaper to attack the Class 3-E students, causing Koro-sensei to rush in and shield them, receiving immense damage in the process. Yanagisawa mocks Koro-sensei for his act, stating that his biggest weakness is, in fact, his students. Koro-sensei retorts with this:
    Koro-sensei: THAT IS PREPOSTEROUS! You're a fool if you think I'll believe it's that cut and dry! These children, they've risked life and limb to save me! What they've gone through just to be here tonight is extraordinary! Their determination... their unflappable spirit... students like these are the greatest gift a teacher could ask for! They are not a hindrance! They are not a weakness! They are my class, and I am proud of each and every one of them! Call it what you will, but when the chips are down, I will give my life to protect them!
  • Significant Name Shift: Karma and Nagisa refer to each other by their first names as Nagisa's parents are separated so he doesn't want any confusion and Karma just likes his name. However, they add on suffixes when talking to each other, demonstrating they aren't that close. It turns out that Karma has always sensed Nagisa's bloodlust and distanced himself from his friend out of fear. Once they resolve their issues, the two drop the suffixes to show their closeness.
  • Single Woman Seeks Good Man: When given the option, the girls of Class E prefer good guys.
    • In the anime, when discussing which of the boys the girls think are most attractive, they all agree that it would easily be Karma, if only he were less evil.
    • In Chapter 90, Nagisa says the kind-hearted and helpful Isogai would undoubtedly be everyone's first choice—he's even attractive enough to get the attention of girls from the main campus.
  • Sinister Geometry: The monsters representing the questions in the school's math finals are fittingly designed with this in mind. The die probability question is imagined as a giant crystalline shape with hexagonal shields circling it, and the last question is an enormous cubical structure with a bust of Venus de Milo on top, descending from above.
  • Slice of Life: Chapter 180.1 takes a break from the students' lives by showing what Koro-sensei does outside of his teaching duties — he's a slovenly bum at home who spends his time hoarding stuff, eating, betting on horse races and meditating in a room full of porn magazines.
  • Sliding Scale of Silliness vs. Seriousness: The story goes from one side to the other whenever it feels like it. At times it occupies both sides of the scale simultaneously. And it works.
  • Small Role, Big Impact: A mouse was the actual cause of the moon's destruction, leading to the prediction that Koro-sensei, who was undergoing the same experiments, will do the same to Earth by March 13th.
  • Solemn Ending Theme: "Mata Kimi ni Aeru Hi" (Until the Day I See You Again), the second ending theme for Season 2.
  • Soundtrack Dissonance: In Season 2 Episode 14, the peaceful piano theme "Odayaka na Asa" (lit. "Calm Morning"), plays when Nagisa, Kayano, and Koro-sensei are cleaning the school's storage shed and reminiscing on the past few months they've been together, and then the theme continues to play as Kayano reveals her tentacles for the first time, getting more distorted as the scene plays out.
  • Spaghetti Kiss: Invoked but ultimately averted in Chapter 74. During the courage test, Koro-sensei dangles a Pocky stick as a setup for Maehara and Okano to do the Pocky game. Neither of the two appreciate the gesture.
  • Split-Screen Reaction: Nagisa earns a seven-panel one after pseudo-assassinating Takaoka.
  • Spoiler Cover: The back cover of volume 15 spoils one of the biggest twists in the manga, by depicting Kayano with her tentacles.
  • Spoiler Title: Episode 21's title averts this, being titled "XX Time" on promos and during the first half of the episode. However, once the mastermind of the hotel arc was revealed to be none other than Takaoka, the episode's title changes to "Takaoka Time", playing the trope straight.
  • Staredown Faceoff: Happens during a baseball game of all things. Early on, Class A counters Class E's bunting strategy by all standing in the infield, not being called out by the biased umpire. Korosensei has Karma mock this favoritism publicly, allowing him and Isogai to perform the same stunt later to avoid a double standard. However, rather than stand a safe distance away, they place themselves only a foot from the batter, Shindo, and stare him down to intimidate him. He quickly panics, unwilling to hurt the other boys, and fails to hit the ball while Karma and Isogai dodge the swing.
  • Status Quo Is God:
    • Enforced by Asano Sr., who developed Kunugigaoka's academic system to give the rest of the school a motive to excel academically. When Koro-sensei tries to defy his system by challenging and motivating Class 3-E, the "terminal section" of the school's worst ninth-graders, to score within the Top 50 on their first midterm exams, Asano Sr. prevents them from excelling by adding several last minute questions to the exam and alerting the entire student body of the change except for Class 3-E.
    • The Chairman takes this up to the next level in Chapter 118 when, after having had enough of Class E garnering respect from the other students in the school, he declares that he's going to pull out all the stops for the finals to ensure that they are crushed once and for all.
    • A straighter example of this trope: One student manages to get a high enough grade to get out of Class 3-E. He returns to the class by the end of his arc after deciding that being in Class A wasn't worth betraying his friends.
  • The Stinger:
    • Episode 8 of the anime ends with Karasuma getting berated on what happened on the Kyoto trip, and is advised on two new students getting ready to join the class (Ritsu and Itona are shown in silhouette).
    • Episode 40 has a big one with the class figuring out their next strategy — going to the ISS to find a potential way to save Koro-sensei.
    • Episode 41 similarly ends with a long scene of the class analyzing the data they acquired from the ISS — revealing that Koro-sensei's chances of blowing up and destroying the Earth is in fact less than 1%.
  • Storming the Castle: The invasion of an enemy home base is the focus of the series' longer arcs. The first one has the students sneaking into a hotel to steal an antidote, and the second has them storming the God of Death's hideout to save Irina.
  • Students Playing Matchmaker: Throughout the series, Irina Jelavic is shown to have deep feelings for Karasuma. The students are aware of this and attempt to help her get with him with minimal success due to Irina's immaturity and Karasuma apparently being Oblivious to Love. After Karasuma reveals he knew all along tells Irina not to let her feelings get in the way of assassination, Irina feels rejected and thinks the students were making fun of her, prompting the students to call Karasuma out on his cold words. After Irina betrays the class, Karasuma realizes he is at fault for how harsh he was and works to make amends with her, even proposing to her in his own waynote .
  • Sudden Soundtrack Stop: In Season 2 Episode 22, a hopeful piano tune plays as Koro-sensei is about to blow the candles on the birthday cake his students had gifted him. The tune is cut short as the cake is attacked from afar by the Reaper's tentacle.
  • Surprisingly Realistic Outcome:
    • Karma learns the hard way that confidence is no substitute for studying when he tanks at math during the first semester finals. Koro-sensei makes sure to point it out so he'll learn from it.
    • Lovro and Irina's competition to "assassinate" Karasuma runs into this. Karasuma isn't about to drop his guard around Irina or fall for any of her tricks, while Lovro is too out of practice to be a credible threat to a special forces soldier like him. In the end, Irina is left with no other option than to make a head on attack, and only succeeds because Karasuma allows her to win.
    • In the Assassination Island arc, the three assassins Takaoka hired are assassins, but they're professional assassins with reputations to uphold and don't share in their employer's sadism. Thus, they don't really want to be responsible for killing an entire class of middle school students. So, when the plan calls for poisoning half the class in order to blackmail the other half, rather than use the deadly virus that Takaoka had no intention of handing over the antidote for, they use a different virus that only looks deadly but will eventually wear off.
    • Chapter 140 reveals that Koro-sensei had sewn his clothes out of hemp plant fiber, shortly after he escaped from Yanagisawa's lab and assumed his current form. The volume release of Chapter 140 includes a little ending illustration showing Koro-sensei itching all over his body, because he wears clothes made out of freshly sewn plant fiber.
    • During the final arc, the mountains where the classes have been held is protected by an elite squad of the world's best soldiers. However, they are not familiar with the territory, and are not as well-trained in stealth and coordination. After all, Class E has been honing their skills and teamwork for a year and know the mountains enough that Karasuma-sensei says they could operate "in there blindfolded". As such, they quickly dispatch most of the soldiers in the mountains with little effort, leaving only their leader, Craig Houjou, left, and even then Class 3-E defeats him by frustrating his attempts to prepare himself, culminating in a Nagisa/Karma combo of a clap stunner and a chokehold.
    • What happens when the public discovers Asano Sr. has segregated all the under-performing students to a run-down school building off the main campus, and actually encouraged other students and faculty to bully them? National public outrage that got so intense that the school board is forced to fire the disgraced Asano Sr., abolish the messed-up system, and surrender the property rights of the Class E building in order to save face and keep Kunugigaoka Academy open.
  • Sweet on Polly Oliver: A kid named Norita Yuji staying at a hotel in the Assassination Island arc becomes utterly infatuated with Nagisa, who is currently disguised as a girl. He makes a return at the School Festival, and 3-E plants to have Nagisa spend more money at their restaurant. While he's disappointed at the reveal that Nagisa is a boy and assumes it to be a lie, he later gives 3-E's restaurant a positive review on his blog to help their revenue.
  • Sweet Tooth: Tentacled beings such as Koro-sensei (who is also a Genius Sweet Tooth), Itona, and Kayano are all shown to have preferences towards sweets. Extra info in the manga's volume releases justifies this by stating that someone with tentacles will require a ton of energy to maintain them, thus they'll naturally be drawn towards foods high in carbs and sugar. Additionally, the Reaper is sometimes shown eating a chocolate bar, and in a twist of fate, he becomes a tentacled being in the finale himself.
  • Synthetic Plague: During the Assassination Island arc, eleven of the students are infected by a potentially fatal virus with varying symptoms — some are still on their feet, while others are vomiting blood, and Terasaka was able to hide his symptoms for hours. This was subverted when it was revealed that Gastro, Grip and Smog withheld using the plague in favor of a relatively harmless stomach flu that will eventually wear off because they only had to make the students think that they would die, and they didn't want the stigma of killing middle-school kids on their reputation, even if it meant defying Takaoka, their psychopathic employer.
  • Takes Ten to Hold:
    • During the Classroom Civil War arc, Nagisa and Karma get into a fight, so the other students intervene. Karma has to be held back with difficulty by two kids who remarked that he's "incredibly strong". Nagisa, who is tiny and the epitome of Weak, but Skilled, is easily restrained by one.
    • One of Korosensei's biggest weaknesses is that, although he can move at Mach 20, he is physically weak and can be restrained if all of his tentacles are held down by, say, an entire classroom of students. The issue with this, of course, is that he can simply move out of the way before anyone can pin him down. Of course, if he's been exhausted by a battle and is now too weak to move...
  • Taking You with Me: Azusa planned this in Extra Chapter 3 with her loan sharks, if Korosensei never showed up for her to kill.
  • Tarot Motifs: In the manga, tarot cards are seen during Lovro's explanation of the Secret Killing Technique. The Chariot represents a powerful opponent, The Fool for the actual technique, and The Moon for an assassin.
  • Team Mercy vs. Team Murder: After the revelation of what Korosensei truly is, the students of Class 3-E divide into two parties. The party led by Nagisa believes that they should find a solution to prevent Korosensei from self-destructing so he can live. Karma's team believes that they should continue trying to kill Korosensei, citing how they've always known him as a target to be killed, and that they've come so far in their goals and shouldn't give up halfway.
  • Technician Versus Performer: The story flips the normal 'performer good, technician bad' attitude with Karma and Nagisa. The two of them have been compared a few times and at least once by Karma himself. He muses that he's faster, stronger, smarter and more skilled than Nagisa in essentially all categories, but he's too much of a showboat to make a proper assassin. Nagisa, the technician, is quiet, looks harmless and is sometimes mistaken for a weak girl, but he's also capable of "killing" casually, looking completely innocent and meek until he's already struck. He's basically mastered the most important skills for an assassin.
  • Techno Babble: The explanation for how Koro-sensei's body produces antimatter is most assuredly 100% this.
  • Thanking the Viewer: The color page in the final chapter has Koro-sensei giving a diploma to the readers.
    • The same thing happens at the end of the second season's final episode and the series when Nagisa, wearing Koro-sensei's gown, waves goodbye to the audience with the words next to him saying "Thanks for watching Assassination Classroom".
  • This Is Reality: During the Cops and Robbers parkour challenge, Sugaya claims that "This isn't some battle manga" as he dismisses his classmates' warnings about Karasuma's overwhelming stealth and agility. A few seconds later, Karasuma appears behind him and catches him in mid-sentence.
  • This Is Wrong on So Many Levels!: Happens at the start of the anime:
    Korosensei: How do you do? I'm the one that blasted your moon. I plan to do the same to Earth next year. Now I'm your teacher. Nice to meet you.
    Students, in perfect unison: There are at least six things wrong with this picture!
    Nagisa, narrating: The feeling was unanimous.
  • Thou Shalt Not Kill: Everyone except for Korosensei is off-limits for Class 3-E. He has only had to explicitly forbid his students from killing humans twice: once before they went up against Gastro, and the other to prevent Nagisa from murdering Takaoka.
  • Throw the Book at Them: In Chapter 17, Nagisa, Karma, Sugino and Okuda knocked their friends' kidnappers right out with a good whack from their guidebooks on the back of the head.
  • Time Skip: Chapter 179 / Episode 47 takes place seven years after graduation.
  • Tokyo Is the Center of the Universe: Downplayed. Kimura's hospital paperwork indicates that Kunugigaoka Town is a suburb somewhere in the Greater Tokyo Metropolitan Area.
  • Town with a Dark Secret: Fukuma Island, a tropical paradise home to several gorgeous beach resorts. The lone hotel on its mountaintop is a luxurious getaway for influential mafias, businessmen, politicians, and assassins who are after Koro-sensei and the students of Class 3-E.
  • Tragic Keepsake: Two characters have these, and both of them just so happen to involve neckties. Koro-sensei's oversized tie was a gift from Aguri Yukimura, his Lost Lenore who motivated him to become a teacher; while Asano Sr.'s sawtooth oak leaf tie clip was gifted to him by his former cram school students, one of which committed suicide and thus motivated Asano Sr. to strengthen his students by enacting his discriminatory "E Class" policy.
  • Training from Hell: Deconstructed with regards to Takaoka's method of teaching, which employs this trope — the students won't stand for it, and all the adults think that he's a psycho.
  • Two Lines, No Waiting: The main plot line of training and attempting to assassinate Koro-sensei is interwoven with the students dealing with various problems in their school and personal lives.
  • Ultimate Final Exam: Played with; the students of class 3-E are forced to endure grueling training exercises for assassination and must study like their lives depend on it in order to complete exams that have already been rigged against them. However, the final exam is actually a relatively normal test, albeit with ridiculously hard questions. It is represented as an intense battle with the questions being grotesque monsters the students must fight with weapons such as pistols and machine guns. In reality, there is no actual danger involved, just extreme stress.
  • Unspoken Plan Guarantee: The relative success of any assassination attempt on Koro-sensei's life is inversely proportional to how many pages are spent explaining the plan. The most successful attempts, such as Nagisa's suicide attack, most of Shiro's schemes, and the assassination on the vacation island are never fully explained to the reader in advance.
    • Takaoka's master plan: Humiliate and beat a student into submission during a "fair fight" using cruel physical and psychological tactics. The details of this scheme take about two chapters to fully explain. Meanwhile, Nagisa, the intended victim, is forced to wing it. Guess who wins the fight?
    • Nagisa explains his tactics in exhaustive detail during his second fight with Takaoka. But the trope is subverted, as his plan proceeds to go off without a hitch.
  • Useless Bystander Parent: Nagisa's father, while clearly a kindly parent, does little to nothing to help his son with Hiromi. While we find out that Nagisa chose to live with his mother, you'd think his father would try to convince him otherwise, or at least be around.
  • Villain Team-Up: Chapter 157 / Episode 42 shows us that Shiro has joined forces with the God of Death.
  • Wake Up, Go to School, Save the World: Inverted. The story is set up like this, but while the students' social and academic lives are challenging, they're trivial compared to the task of killing Koro-sensei.
  • We Need a Distraction:
    • Phase 1 of Class 3-E's revenge plot against the students who bullied Maehara: Nagisa and Kayano, disguised as an elderly couple, distract the bullies at a cafe while Hayami and Chiba sneak homemade laxatives into their drinks.
    • When it seems like Koro-sensei is about to discover Kataoka's plan to assassinate him in the water, Nagisa steps in to take advantage of his weaknesses ("he's very worried about appearances") by taunting him about some fan-letters to a big-breasted actress he found on Koro-sensei's desk.
    • The Assassination Island arc employed this trope several times. Makes sense, since they need to advance quietly to their goal on the top floor of a hotel. Irina uses her feminine wiles to distract a group of guards to buy time for her students; Kimura insults two guards to make them chase him.
  • Weaponized Animal: There are Dobermanns trained to fire the machine guns strapped to their backs in the God of Death's hideout.
  • Weird Moon: It is a permanent crescent with overly long horns, thanks to Koro-sensei blowing up 70% of it in the beginning.
  • Wham Episode:
    • Chapter 59 ends with half of the students discovering that they have been poisoned, with the culprit demanding that they bring Koro-Sensei, who is immobilized and cannot help them, to a hotel if they want to get the cure.
    • Chapter 68 reveals the mastermind of the student's poisoning to be none other than Takaoka.
    • Chapter 128, which contains the biggest plot twist in the entire series. The event triggers a series of wham episodes that contain major plot revelations that had been a mystery up until that point. You'll never look at Kayano the same way again. Amazingly, the twist actually seems to come out of nowhere...until you go back and realize that the author was laying out some very subtle clues.
    • The following chapter follows suit with the revelation that Kayano's name isn't even Kaede Kayano. It's Akari Yukimura and she's actually the younger sister of Aguri Yukimura, class E's former teacher and the woman from Koro-sensei's past.
    • Chapter 133 reveals that Koro-sensei was the Reaper before the one Class 3-E, Karasuma and Irina defeated earlier.
    • Chapter 134 might be the Whammiest yet: Koro-sensei's human form is shown for the first time, and Shiro was one of the scientists experimenting on him. Also, the Reaper defeated by Karasuma used to be an apprentice of Koro-sensei, who is implied to be the assassin who murdered his father.
    • Chapter 138 is another big Wham: Koro-sensei did not actually destroy the Moon. It was caused by one of Shiro's experiments, where he injected a mouse with antimatter organs to see what would happen if it died of natural causes. Turns out, not only does the procedure significantly shorten the subject's lifespan, but when an antimatter enhanced being naturally dies, it creates a massively destructive antimatter chain reaction. Koro-sensei's lifespan will end on March 13, suggesting that he wants Class E to kill him to prevent the inevitable disaster.
    • Chapter 164: The beginning of the end. The government has a Kill Sat that can kill Koro-sensei and they've trapped him on the mountain until they can fully charge it. They've also exposed Koro-sensei to the public in order to demonize him as the monster who held Class E as hostages.
    • Chapter 173: Kayano gets stabbed through by the second God of Death. And Korosensei is not happy.
  • Wham Line:
    • For Karasuma during the cops and robbers game, "You're more than a minute away from the pool." Karasuma then realizes he's been tricked and the kids have won.
    • The reveal of the identity of Shiro's ultimate assassin:
      Shiro: All right, number two. Time to begin. As bearers of the same bloodlust, let us kill number one.
    • Extra Chapter 3 ends with this line:
      Azusa: Yes... everyone is so kind... and thanks to that... my carefully laid plans were almost ruined.
  • Wham Shot:
  • "Where Are They Now?" Epilogue: In two phases, covering Chapters 179-180:
    • The first half of Chapter 179 focuses on the immediate aftermath of Koro-sensei's death at the hands of Class 3-E. Shiro/Yanagisawa survives being blown away into the anti-tentacle barrier, but the damage to his tentacle-infused body has left him a vegetable, while his experiments have been finally canned by the government. Public outrage over revelations of Kunugigaoka's discriminatory policies forced Asano Sr. to step down, though he not only seems to have anticipated it, but also sees it as an opportunity to start anew. Class 3-E used part of their reward to support their later education, donate to some acquaintances, and buy the entire mountain they used to call their classroom, while the rest was returned to the government.
    • The latter half of Chapter 179 and the entirety of Chapter 180 fast-forwards to seven years later. The moon has collapsed and coalesced again into a spherical form while it was pulled closer by Earth's gravity, implicitly normalizing the tides to pre-explosion levels. Karasuma and Irina are now married and work together as counterterrorist agents. And by the looks of it, Class 3-E's alumni have utilized everything they learned to lead successful and meaningful lives — Ritsu is now a fully-sentient being, Okano the leader of a university athletics club (which uses her old turf as training grounds), Kurahashi an ecotourist guide (using the same mountain for explorations), Takebayashi and Okuda developers of universal artificial blood, Sugino a college baseball superstar, Terasaka an apprentice to a powerful politician, Yoshida, Muramatsu and Itona inheritors to their family businesses, Nakamura a university student in London, Hazama a librarian, Kanzaki a caregiver, Sugaya an experimental artist, Karma an aspiring statesman, Kayano has returned to showbiz and is currently starring in a popular drama, and Nagisa is now teacher to a class of delinquents, while the rest are implied to be most likely finishing their education and starting new careers as well — even as they never forget to keep in contact with each other.
  • Why Don't You Just Shoot Him?: Justified during the civil war among Class 3-E. The students are divided over whether they should kill Koro-sensei or try to find a way to save him, so they decide to play a game of paintball to decide their stance on the issue. The game ends up being a one-on-one showdown between Nagisa and Karma. Nagisa is in a position where he can just snipe Karma, who's in an open field and goads Nagisa into fighting him in close combat. Nagisa ultimately accepts the challenge rather than snipe Karma, because if he won through such an underhanded method, the class wouldn't accept the result and still be divided. The fight ends with Nagisa restraining Karma and overpowering him, but Karma has a free hand and is close enough to his painted knife to grab it and beat Nagisa. Karma doesn't go for his knife and accepts his loss for the same reason Nagisa didn't snipe him.
  • Will They or Won't They?: It is never officially revealed if Nagisa and Kayano got together even after the epilogue.
  • Wise Beyond Their Years: The two young boys at the nursery act unusually mature for their age.
    First Boy: The action looks so real.
    Second Boy:'s much more stimulating than the Disney monopolized Hollywood.
  • Wishing for More Wishes: When class 3-E challenges 3-A, with the condition that the losing class must follow one order from the winner, 3-A immediately puts together a massive document full of requirements and commands (including, in effect, "do whatever we tell you to") with the intended order of "obey this document".
  • Witch with a Capital "B": The English translation preserves the students' nicknaming Irina "Bitch-sensei" by calling her "Ms. Vitch". However, volume 7 does start calling her Ms. Bitch.
  • The Worf Effect: Lovro the hitman dealer was a powerful, talented assassin during his younger days. Despite being currently retired, he's still skilled enough to effortlessly subdue Irina. He's no match for the God of Death, a mysterious figure who abruptly kills Lovro within ten seconds of making his presence known to him. Except not quite.
  • World of Technicolor Hair: The class includes students (who are all Japanese) with hair colors ranging from normal black and brown, to unusual but still realistic blonde and orange (Rio and Hinano), to blue (Nagisa), green (Kaede),note  and bright red (Karma).
  • World Tour: In Chapter 162, Koro-sensei puts all of his students into giant bags and takes them traveling around the world to take pictures for the class yearbook. The world tour itself happens offscreen; the very next chapter reveals that they went to 30 countries in a single day, but had no time to actually go sightseeing because Koro-sensei only has time to take their pictures before flying off into the next country.
  • Writers Cannot Do Math: Chapter 158 is set on Valentine's Day. Problem is that, two chapters ago, it was stated that there are 26 days remaining until the deadline. Subtracting 26 days from the deadline (March 13) would place Chapter 156 at February 15...the day after Valentine's Day.
  • Xanatos Gambit: Ms. Azusa's plot in the "Extra Class" story. If Koro-sensei tried to rescue her from the loan shark she'd have killed him with the suicide bomb and won the reward for her daughter, while if he didn't she'd just have killed herself and the loan shark and the daughter would get her life insurance money, since nobody would suspect a respectable, blind, woman of the bombing and it would be put down to a gang war.
  • Your Size May Vary: Often used artistically to emphasize the David vs. Goliath aspect of the fights between Class E and their opponents.
    • Very prominent with Nagisa and Takaoka. Sometimes they would be drawn close to their actual relative proportions, and sometimes Takaoka would look twice as tall as Nagisa.
    • The foreign exchange students participating in the Bo-Taoshi challenge do NOT look the same age as middle-schoolers. They seem to grow in size as the match progresses.

    Tropes in the Episode 0: Encounter Time OVA 
  • Diegetic Switch: The short opens with Ave Maria playing in the background, as Karasuma approaches the room Koro-sensei is held up in. Then it's revealed that the piece was playing through a speaker inside Koro-sensei's holding, and the speaker is turned off after Karasuma enters the room.
  • Episode Zero: The Beginning: The OVA is titled Episode 0, and is a prequel telling how Koro-sensei and Karasuma first met.
  • Intimidation Demonstration: According to Koro-sensei in this short, he blew up the Moon as a demonstration to show world leaders what he's capable of.
  • Nested Story Reveal: In the end, Karasuma reveals that the short's whole story was made up by Koro-sensei. He first found Koro-sensei already inside the teacher's room, not in a secret government facility; and the fight between the two never happened.
  • O.O.C. Is Serious Business: Throughout the short, the usually goofy Koro-sensei has a menacing, deep tone to his voice that doesn't ever let up. Additionally, after Koro-sensei defeats Karasuma at the end, the usually stoic government agent smiles, comments on how handsome the former is, and hugs him happily. It's later revealed that the whole short is made up by Koro-sensei himself, hence the OOC moments and the self-ego boost.
  • Pocket Protector: Karasuma manages to stab Koro-sensei in his chest during their fight, but Koro-sensei reveals that the knife had dug into his copy of Also sprach Zarathustra that he had saved inside his coat prior. Not that it matters, since Koro-sensei later demonstrates that regular knives will simply melt on contact with his body.
  • Secret Test of Character: Koro-sensei reveals to Karasuma that their fight is actually a test held by him to see if Karasuma is capable of being his supervisor.


Video Example(s):

Alternative Title(s): Ansatsu Kyoushitsu


Itona vs. the Classroom Wall

In demonstration of his strength, new student Itona makes his entrance by demolishing the rear wall of Class 3-E, much to the students' chagrin.

How well does it match the trope?

4.92 (52 votes)

Example of:

Main / ThereWasADoor

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