Manga: Assassination Classroom

aka: Ansatsu Kyoushitsu
Just another day in Class 3-E.

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

Every morning, the students of Kunugigaoka Middle School's Class 3-E greet their teacher — a bizarre, octopus-like being that can move at libera top speed of mach 20, aptly nicknamed Koro-sensei — with a massive firing squad.

This super creature was responsible for the partial destruction of the moon, permanently not crescent-shaped, and has announced his intention to do the same thing to Earth in exactly one year. Koro-sensei 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 its students to try and kill him however they’d like to. Can the students successfully take Koro-sensei down and save the world despite the fact that he’s very cunning, nearly invincible, and definitely the best teacher they've ever had?

Despite the outlandish and somewhat foreboding premise, Assassination Classroom (titled Ansatsu Kyoushitsu in Japan) 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 is currently serialized in Weekly Shonen Jump and licensed for English volume release by VIZ Media. Two OVAs premiered during the 2013 and 2014 Jump Super Anime Tours, and a live-action movie adaptation premiered on March 21st, 2015. Funimation has picked up the rights to stream and dub the ongoing two cour TV anime adaptation, which premiered on January 9, 2015. In Australia, SBS 2 has started airing the anime.

Place all character-related tropes in the character page.

This series provides examples of:

  • 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.
  • Abusive Parents: The entire reason that Nagisa is capable of reading people so easily, with a single glance, is because he's needed to learn how to do it in order to survive the monster that is his mother, who can go from zero to a 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 make all previous jokes about his androgyny a Funny Aneurysm. Nagisa's father isn't much better, but his is more Parental Neglect, because despite knowing how violent the mother can be, he just pretty much left his son to deal with it alone, only showing up once in a while.
  • 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 because he knew that the explosion was strong enough to severely injure whoever carried it out.
  • Adaptation Distillation: The anime had to remove some comedic moments and minor information about some of the characters from manga to ensure they can fit in at least 2-3 chapters in one episode.
  • 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.
  • Adapted Out:
    • Maehara's limelight chapters (23 and 24) 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) also got skipped.
    • Meg's limelight chapters (44 and 45) also didn't make the cut.
  • All Girls Want Bad Boys: Inverted. 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 was less evil.
    • In Chapter 90, Nagisa says the kindhearted and helpful Isogai would be doubtlessly everyone's first answer for number one class E ikemen; enough so that he still attracts students from the main building.
  • All There in the Manual: The Official Character Guide reveals a fair bit of information about the students, particularly relationship wise.
  • Animal Motifs: The Chairman and centipedes. Koro-sensei with octopods.
  • 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 / Spoiler 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 Korosensei 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 crescent moon on Koro-sensei's tie. It's often used as a reminder of just how powerful Koro-sensei is.
  • Armor-Piercing Slap: Delivered the Koro-Sensei way after the students get too confident in themselves, decide to disobey Karasuma's orders by trying out their new free-running skills in a civilian area, and end up injuring a bystander in the process.
  • Artistic License – Geography: Actually, Koro-Sensei passed the Philippines the first time he crossed the world in his drawing song. It's Indonesia he crossed when crossing back to Dubai.
  • Artistic License – Gun Safety: Mostly averted, except for a few instances of lax trigger discipline. The anime even clears those up.
  • 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.
  • Axes at School: They're rubber knives and pellet guns that are only harmful to Koro-sensei, but they're still rather alarming.
  • 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.
  • 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 Class-E delinquents (not counting Karma). It's even lampshaded when two girls in a higher-ranking class note that Class-E's phys ed 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, Extreme Anger) if anyone tries to push his Berserk Button. Usually occurs when someone tries to hurt his students or when he sees Itona Horibe's tentacles.
      • Inverted when you consider his original appearance. When he was still human, he was both a certified ikemen and a cold-blooded assassin known as the original "God of Death". Such a shame that he did not remain that way after the anti-matter experiments done on him turned him into what he looks like today.
    • Averted with Kaho Tsuchiya of Class 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 who turned an extremely skilled but still human assassin into the inhuman Korosensei 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: A cultural one, for Brazil. 7 to 1. Triggered when Koro-sensei is vacationing there, thinking up math problems.
  • Big Damn Kiss: Nagisa pulls a 15-hit combo French kiss on Kayano in order to knock her out so that Koro-sensei could remove her tentacles.
  • Bitch in Sheep's Clothing: Irina Jelavic is a manipulative honeypot assassin and all-round mean person. Earning the nickname "Professor Bitch" from the students. She stops being mean to the class after her initial introduction but is no less of a temptress afterwards.
  • Black Comedy Rape: Implied in Chapter 9, 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...
  • 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 (rather unblandly named) 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.
  • 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.
  • 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!"
  • Breather Episode: After the Hotel arc, the longest and most intense arc of the series up to that point, Koro-sensei decides to lighten up the mood by treating the kids to a test of courage.
  • Broken Aesop / Fantastic Aesop: The story's message that individualized education in a caring environment is superior to a colder and less personalized style is rather undermined by the fact that Koro-sensei is explicitly superhuman. A real human being is flat out incapable of the kinds of stunts he pulls because they can't move at superspeed, don't have perfect memory or genius level intellect, can't memorize dozens of textbooks and can't hold multiple conversations at once. Nor can they be everywhere at once to stop bullying or attacks. It may be perfectly true that the Japanese educational system is deeply flawed in many respects, but expecting a human being in charge of dozens or hundreds of students to be able to keep up with Koro-sensei is impossible.
  • Buxom Is Better: Koro-Sensei has a clear preference for big breasted women.
  • 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, and in chapter 76 the two of them have breakfast together at a sushi bar.
    • In Chapter 51, Kayano reads a magazine on "Puddings of the World" instead of studying for finals. Her assassination attempt in Chapter 80 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.
  • 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 Giant, and they now share the same voice actor, Subaru Kimura.
    • Asano Gakushuu shares the same voice actor as well as characteristics as another famous genius.
  • Cast Of Snow Flakes: No two major characters look alike.
  • Cerebus Rollercoaster: There are a few Story Arcs peppered throughout the manga that are significantly darker in tone than the rest, which become very jarring in contrast to the series' usual comedic, slice-of-life fare.
    • The most outstanding examples include the Assassination Island arc and the God of Death arc, which puts several characters' lives at risk.
    • Things get very dark again after the Wham Episode that is Chapter 128, which features Akari's reveal and Koro-sensei's backstory. Things get lighter again though after the entire class resolves to save Koro-sensei.
  • 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 combo 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.
  • 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 comprise of 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.
  • 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.
  • Cool Guns: Every gun shown in the series is real, and rendered with exquisite attention to detail. The guns the students use are said to be airgun versions of the genuine articles, but looking at them, you can't tell the difference.
    • The student's standard armaments are the M1911 pistol and the M4 MOE carbine. Rarely, they are also seen using SPAS 12 shotguns and MP5K submachine guns.
    • Red Eye's rifle is an Accuracy International Arctic Warfare Suppressed. The AWS is a variant of the Arctic Warfare series visually distinguished by its lack of a muzzle break, and meant to fire subsonic ammunition. This fits Karasuma's description of the anti-sensei rifle bullets. They cannot be fired at supersonic velocities.
    • Gastro's weapon of choice is the S&W Model 60 revolver. The guns Chiba and Hayami have when fighting him are of the same type. Notably, the M60 has a 5-round cylinder, and Gastro is shown firing the correct number of shots before having to reload.
  • Crazy-Prepared: Koro-sensei's "guidebooks".
  • 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 never fall for the same trick again. Fortunately, Koro-sensei has a hard time overcoming his weaknesses, which the students utilize to their advantage repeatedly.
  • Crossover:
  • Curb-Stomp Battle: Akira Takaoka, elite soldier and special forces instructor, versus Nagisa Shiota, 14-year-old middle school student with three months of assassin training. Nagisa wins in under 10 seconds because he treats it as an assassin, 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.
  • Dancing Theme: Both of the anime's opening themes.
  • David Versus Goliath: Nagisa vs. Takaoka.
  • 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.
  • Decoy Protagonist: Deliberately invoked by Kaede who turned Nagisa into a protagonist so attention would be diverted towards him and away from Kaede herself.
  • 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 also immobile for 24 hours. When Takaoka and his hitmen assault the class, the remaining 15 students and the other two teachers have to handle the situation for 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 was already over.
  • Detonation Moon: Koro-sensei's first major demonstration of power: he basically reduced it to a permanent crescent by destroying 70 percent of its volume.
  • Did You Just Flip Off Cthulhu?: Not flipping him off, but scolding him, which is in line with the spirit of the trope. Kataoka, Yada and Okano give Koro-sensei a pretty good telling off when he pulls up Class E's flower bed as part of an attempt to look cool. They make him replant the whole thing at regular speed as punishment. Afterwards, the class holds an assassination rally with a handicap: Koro-sensei gets tied up and dangled from a tree branch like a pinata while the class tries to hit him with anti-sensei knives taped to long poles.
  • "Do It Yourself" Theme Tune: Both openings for the anime adaptation are sung in-character by the voice actors of Nagisa, Karma, Kayano, Isogai, and Maehara. In Episodes 7 and 8, Isogai and Maehara are temporarily replaced by Sugino, Okuda, and Kanzaki to mirror the events of the Kyoto field trip.
  • Doorstopper: What Koro-sensei produces every time he comes up with a "guidebook" for class excursions. One octopode's guide is another man's industrialized carbon-capture method—with indices, cross-references, info-panels, bullet points and plot-significance.
  • 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.
  • 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 him like we do now, it was an extreme action to take. However, considering his backstory and what this post points out, he was just starting to get into his new identity.
  • Easter Egg: 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 slut".
  • Elevator School: Kunugigaoka is one, but if you're in class E at the end of 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 in 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 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!
  • Even Evil Has Standards:
    • Professional standards no less. No assassin worth his salt wants to be known as the person who murdered an entire class of middle-schoolers, regardless of moral compunctions, because his name would be dirt to his contemporaries thereafter.
    • 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 A's modest victory over Class E at the school festival, suggests that he should have achieved an overwhelming victory by sabotaging Class E's ramen restaurant and poisoning their food. As of the end of chapter 118, he begins to see the monster his father truly is.
  • 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 an artificial being was the only 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 the opening sequence after her introduction in Episode 4.
    • Episode 7 follows six students who group up for their class trip to Kyoto. The OP for that episode and the following one is sung by those same six students instead of the ones who usually sing the theme tune.
    • Ritsu can be seen near the end of the OP starting from Episode 7, despite not being formally introduced until Episode 9, from Episode 10 on she appears throughout the opening.
    • Episode 18 overhauls the second OP's 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.
  • Failure Is the Only Option: The story will end as soon as someone successfully assassinates Koro-sensei. Of course none of those 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-E visit a festival to commemorate the end of summer. The kids, thanks to their assassination training, turn out to be far too skilled at the game booths. Hayami and Chiba in particular end up banned from the shooting range after practically robbing the stand of its prizes.
  • Flash Back Echo:
    • When Koro-sensei notices a fragment of sizzling gunpowder from Nagisa's failed assassination attempt, it triggers a cryptic flashback involving the remains of a destroyed, burning laboratory, a mysterious woman with a bleeding stomach, and a tentacled, human-like figure cradling her in its arms. The woman is Aguri Yukimura, Class E's previous homeroom teacher.
    • When Itona reveals his tentacles for the first time, Koro-sensei becomes furious as he briefly recalls a tentacle piercing the chest of the mysterious woman. Aguri was pierced by a similar tentacle-based weapon 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 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 knife, and they use a tennis net instead of a badminton or volleyball net.
  • Five Rounds Rapid: Inverted. Irina's men dismiss airsoft weapons in favor of machine guns, not knowing that Korosensei's body dissolves lead but is blown to chunks by airsoft pellets made of special material. Generally speaking, knives and airsoft pellets brought him closer to being destroyed than nuclear weapons.
  • 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.
    • 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".
    • 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 "God of Death" 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 telling the truth.
    • 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. Go back to Chapter 29 and read this page.
  • 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.
  • 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 the 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 name: Justice, which isn't revealed until later in the manga.
  • The Gambling Addict: One of The Chairman's first cruel acts on opening his school was to turn a student into a hopeless gambling addict as revenge for him bullying a student from his old cram school until he commited suicide.
  • Gender Neutral Pronoun:
    • 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.
    • In a similar vein, 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.
  • 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.
  • 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 hoarde 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.
  • 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).
  • Gratuitous IPA English: On the cover page of chapter 55, the word assassination is rendered as əsˈæsənˌeɪʃən, which would actually be assassanation, 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.
  • The Guards Must Be Crazy: Those two guards on the top floor of the hotel in the Island arc are trained agents, yet both of them immediately left their spot to chase after a kid just because he insulted them. Not to mention they got outrun by a kid (a kid trained in assassinating and the fastest runner, but still...).
  • Humans Are the Real Monsters: Aside from his stated desire to blow up the Earth, Korosensei does nothing bad within the scope of the series. Humans, on the other hand, have more than proven themselves to be capable of being ruthless monsters.
  • Hijacked by Ganon: Takaoka in the Island arc.
  • 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.
  • Idiosyncratic Episode Naming: So far all of the chapters have the word "time" in them.
    • Possibly intended as a reminder that there is a deadline for how long the students have left to kill Koro-sensei.
    • May also be interpreted as a class "period" (a loose synonym for "time"). Some chapters even have the exact same title as a previous chapter with the phrase "2nd Hour" added to the end of it. It meshes nicely with the series' classroom theme.
  • 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 chpater 89.
  • Japanese Ranguage: Used a lot with regards to Irina Jelavic, the foreign 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.
  • Jerk Ass: 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 the snipers' true hiding spot underneath the ocean.
  • 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 interrupt a rampaging Kayano.
  • 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 off Class E students, Koro-sensei helps them to get their revenge or something eventually happens to make them regret it, unless the Chairman appears to intervene.
  • Laughing Mad: In the climax of the Assassination Island arc, Takaoka breaks into a fit of hysterical laughter when he blows up the antidote used to cure the students, further pissing off Nagisa.
  • 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 was lazy about studying and saw his grades slip compared to midterms, and Gakushuu Asano who, along with his clique, lost several "best in grade" positions to Class-E.
    Koro-sensei: For those with a high level of aptitude... the sooner they know the frustration of defeat, the greater their growth will be.
  • Lethal Joke Technique: Combined with Violation of Common Sense. Lovro taught Nagisa a technique which basically amounted 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 silly move, and leave him open for another sneak attack. The God of Death developed this further, not only disrupting concentration, but utterly shattering the psyche.
  • Letting the Air Out of the Band: Done several times throughout the anime for comedic effect. For example, in 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 students earn perfect scores on the Home Economics exam, which he completely forgot about because it's generally not considered one of the five main subjects.
  • 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 identity is revealed.
  • 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 she reels him in and threatens to suffocate him.
  • Masquerade: Aside from the Chairman, 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. 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 through a lot of trouble compensating for the work 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 at Class 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 he 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, the Chairman replies, "Not everything in this world can be solved with speed". Later in the story, Koro-sensei repeats this line to his students after revealing the mountainside oasis 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 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 its a bunch of students assigned to kill a dude whose skilled at killing dudes whose wants and teaches the students to kill him.
  • 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 the 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 between hilarious, tragic, and back again.
    • Chapter 83 is a comedy chapter about Koro-Sensei being framed as an underwear thief. Then Shiro and Itona spring their trap on the last few pages...
    • Chapter 98 has the main cast showing to 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 Eyes. Irina is next.
  • 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, or aiming it at a hostage, since his ability to defend others with his mach speed is relatively lackluster.
  • 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 do 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. 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 matsutaki) 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 yard, teach all students simultaneously, get some snow cone ice from 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.
  • 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.
  • 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.
  • 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.
  • Non-Standard Character Design: Koro-sensei and the Chairman 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. The Chairman 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 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-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 up the stage for the God of Death to make his move.
  • Offscreen Villainy: Aside from his shameless perversion, Korosensei have not done anything that is morally wrong on-screen. And yet, he has all but destroyed the Moon in the backstory and plans to do the same to the Earth in close future. No info is provided on whether he massacred the combined armies of the world trying to kill him or would rather just No Sell their barrage.
  • 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.
  • 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.
    • Lovro teaches the basics of the skill to Nagisa, who eventually uses it to defeat Takaoka during their rematch at the climax of the Hotel arc.
    • When the God of Death 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".
  • 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.
  • Overly Long Name: The anime that Takebayashi recommends to Koro-sensei is titled, "Ore No Imouto Ga Totsuzen Hiroshima-Fan Ni Natta No Wa Kareshi No Eikyou Ni Chigai Nai Ken Ni Tsuite".note , clearly poking fun at Oreimo as well as the general tendency for Japanese light novels' Lensman Arms Race of long titles and annoying kanji.
  • 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.
  • 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 they would have to be crazy to kill a bunch of middle class Japanese teenagers just because some nutty guy wants them to. Their reputations would be damaged and they would be in far too much spotlight and legal trouble to make it nearly worth the amount they were being paid.
  • Precision F-Strike: Used during the opening for Episode 17, when Kunudon finds out that Class E gets to go on the exclusive vacation. It is the only time in Season 1 of the anime that the "f-bomb" is used.
  • Pretty Little Headshots: Averted, as much as is possible for a manga aimed at this age group. When the God of Death 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.
  • 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.
  • Pun: Tons, most of which incorporate "殺", the kanji for "kill".
    • Of particular note, Koro-sensei's name was chosen for him by the class for sounding similar to "korosenai," the potential-negative form of the verb meaning "to kill," so it means "cannot kill" or "cannot be killed."
    • Another reoccurring pun revolves around the exam questions, which are always depicted as gigantic monsters. The kanji for "question" is "mon" (門), so the monsters (モンスター) become "problem behemoths" (門スター).
  • 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.
  • Reality Ensues: Karma learns the hard way that confidence and acting cool are no substitute for studying when he tanks his math final. Koro-Sensei makes sure to point it out so he'll learn from it.
  • Reassignment Backfire: The Chairman set up Class 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 Korosensei comes in and starts improving the moral of Class E, while simultaneously improving their school work; though the other classes initially don't notice this growth, attempts by the Chairman and his son Gakushuu to beat Class E back down only make the other classes respect the growth Class E makes. Come chapter 123, when Class A finds themselves beaten by Class E's scores, the Chairman finds that the students of Class A would almost welcome going to Class E in order to improve like Class E did, while simultaneously stating that the Chairman's teaching method doesn't work. Suffice to say, the Chairman does not approve of these developments.
  • Recycled In Space: It's Great Teacher Onizuka. With an alien.
    • Which is funny because they DO go to space.
  • 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).
  • 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 bust.
    • 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.
  • Save Our Students:
    • Koro-sensei is at Kunugigaoka Middle School to help their lowest-performing students excel... through a liberal application of super powers and some rather unusual extracurricular activities. Avoids Glurge by making his successes not a matter of whether he cares or not, but due to the fact that he is just an inhumanly good teacher.
    • 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.
  • 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.
  • 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.
  • Shaggy Dog Story: A mysterious person infects Class-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 students definitely ship Irina and Karasuma and try to help them get together.
    • Following the Hotel arc, Koro-sensei tries to use the Test of Courage as this. He pairs together certain boy/girl sets and tries to use the scares to get them to cling to each other. It doesn't really go as planned.
  • Shout-Out: The series has so many shout-outs to current events, video games, and manga that it needed its own page.
  • Sliding Scale of Silliness Versus 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.
  • Something Completely Different: 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.
  • Species Lost and Found: The Japanese river otter, declared extinct in 2012, appears in chapters 56 and 88.
  • Spell My Name with an "S":
    • It took a while for the official readings for everyone's names to come out.
    • Korosensei, Koro Sensei, or Koro-Sensei? Most official translations use "Koro Sensei", but opinions still differ.
  • Split-Screen Reaction: Nagisa earns a seven-panel one after pseudo-assassinating Takaoka.
  • Status Quo Is God:
    • Enforced by the Chairman, who developed the Class E 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 to score within the Top 50 on their first mid-term exams, the Chairman 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 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.
  • Stockholm Syndrome: What Takeoka's "9 sticks to 1 carrot" s training stradegy invokes.
  • 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.
  • Surprisingly Good English: Instances of written English in the manga and the anime are all well written and grammatically correct.
    • In an interesting version of paying the trope straight by subverting it, the English in one question on the midterms is not grammatically correct, nor is it supposed be as it's really a quote from The Catcher in the Rye which does not use proper English. The student who translated it literally was marked down, while the one who recognized it as a quote and wrote it as it would be in the English version of the novel such got the points.
    • Subverted in the anime in terms of spoken English; though Irina's isn't bad, if Engrishy, Karasuma's and Lovro's are difficult to understand without subtitles.
  • Synthetic Plague:
    • Eleven students of Class E get infected by one at the end of chapter 60. Early symptoms differ between people, so some of them are still on their feet while others are vomiting blood, and Terasaka is able to hide his symptoms for hours. All of a sudden, things just got extremely real.
    • Later, it's revealed that the assassins withheld using the plague and instead used a variation of the stomach flu because they only had to make the students think that they would die and they didn't want actually killing a class of high school students on their reputation.
  • Tarot Motifs: Seen in 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.
  • Technician vs. 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, very level headed and looks completely innocent and nonthreatening until he's already struck. He's basically mastered the most important skill for an assassin.
  • Techno Babble: The explanation for how Koro-sensei's body produces antimatter is most assuredly 100% this.
  • Theme Tune Cameo: In Episode 20, the second opening theme plays as the club's background music when Yuuji tries to impress the girls with his dance moves.
  • 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 of Karasuma's overwhelming stealth and agility. A few seconds later, Karasuma appears behind him and catches him in mid-sentence.
  • 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: Fukumajima 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.
  • 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 lives.
  • 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.
    • 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.
  • 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.
  • Villain Team-Up: Chapter 157 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.
  • Weaponized Animal: There are dobermans trained to fire the machine guns strapped to their backs in the God of Death's hideout.
  • We Need a Distraction:
    • Phase 1 of Class E's revenge plot against the students who bullied Maehara: Nagisa and Kayano, disguised as an elderly couple, distract the bullies at a cafe so that Hayami and Chiba can shoot 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 skills to distract a group of guards to buy times for her student; Kimura insults two guards to make them chase him.
  • Wham Episode: 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 God of Death before the one that Class-E and teachers defeated during the God of Death arc.
    • 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 God of Death 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.
  • 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.
  • 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.
  • Witch with a Capital B: The English translation preserves the students' nicknaming Irina "Bitch-sensei" by calling her "Ms. Vitch."
  • 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.
  • Writers Cannot Do Math: Chapter 158 is set on Valentines 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 Valentines Day.
  • 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.

Alternative Title(s):

Ansatsu Kyoushitsu