History Characters / AssassinationClassroomClass3EMain

!!#11: Nagisa Shiota (潮田 渚 ''Shiota Nagisa'')

!!#1: Karma Akabane (赤羽 業 ''Akabane Karuma'')

!!#7: Kaede Kayano (茅野 カエデ ''Kayano Kaede'')

* OlderAndWiser: Played with. In the Assassination Classroom Movie "365 Days", [[spoiler:which shows both Nagisa and Karma revisiting their school after the time-skip, he seems more mature and less "crazy" as he reflects upon everything that happened with Class 3-E... till he goes back to his sly self and starts picking on Nagisa.]]

* {{Sadist}}: Coming in hand-in-hand with his BloodKnight tendencies, Karma clearly gets a kick out of bringing cruel and unusual harm to people, and often looks for excuses to get involved in fights or pull nasty tricks. He does, however, [[EveryoneHasStandards draw the line at hurting people who he feels haven't done anything to deserve it]], and mostly limits himself to being BullyHunter. His propensity for violence is undeniable, though, as during the [[spoiler:class Civil war game]] Karma's inner monologue displays a disturbing amount of genuine, ''gleeful'' desire to beat [[spoiler: Nagisa]], one of his closest friends, to a bloody pulp.

* YourWorstMemory: When he throws himself from a cliff as part of his SuicideAttack on Koro-sensei, [[DissonantLaughter he laughs manically for a bit]], exclaiming "[[MyLifeFlashedBeforeMyEyes Wow! everything is flashing before my eyes!]]" as he recalls the moment where a teacher had let him down by breaking his promise to Karma. Taken UpToEleven when the teacher's face starts withering away slowly, till he's nothing but a talking skull in Karma's mind and then he concludes that the teacher is dead to him. That one unforgettable memory was the defining moment that made Karma lose his trust in teachers.

* ItsPersonal: Unlike the other students, she has a personal reason to kill Koro-sensei. To avenge her sister Aguri.

* ReplacementGoldfish: Shiro states that he intended to take her for a truly villainous version of replacement of her older sister, after she got stabbed.

* BreakTheCutie: In the space of one day, Kayano realizes that her excruciating year-long vendetta against Koro-sensei was all for nothing, that she was really in love with a boy she told she despised, and that she nearly murdered a (relatively) innocent man. She spends the next two weeks recovering both emotionally and physically.

--> ''[reading about tentacles]'':'In exchange for overwhelming strength, lack of maintenance causes fierce pain...?' [[DealWithTheDevil Fine by me]].''

* HeroicSacrifice: In the final battle, she draws the enemies' attention so that Koro-sensei can recupirate, knowing full well it's unlikely she'll survive but still doing so as part of her [[TheAtoner atonement.]] She is ImpaledWithExtremePrejudice as a result.

* SweetTooth: Chapter 80 reveals her love for pudding. She gets the opportunity to use pudding for an assassination. This makes her similar to Koro-sensei and Itona.

* AmbiguouslyBi: Karma has shown himself to be interested in Okuda, and his friendship with Nagisa could easily be extended to him having feelings for Nagisa. Karma also does some very suggestive moves in the anime when suggesting to Terasuka a way to deal with Itona at the waterfall fight, though it may be part of his [[IShallTauntYou Taunting]] nature.

* DudeLooksLikeALady: He has GirlishPigtails and a slim, feminine-looking body (minus boobs). This is lampshaded during Chapter 43's pool time, where Nakamura saw him wearing trunks and admits that until then she was confused about his true gender. He also only needs female clothing and some accessories to pass up for a girl in Chapter 66 / Season 1 Episode 19 and accidentally charm another boy. [[spoiler:This is deconstructed, however, when it was revealed that his mother deliberately set this up because she always wanted a daughter.]]

* CorruptBureaucrat: What he wants to be when he grows up. [[spoiler:In the epilogue, he enters a government admission test, with the intention to carve his name into Japan's political history.]]

* ButterflyKnife: For added cool, the anime gives Karma one during his introductory attack on Koro-sensei. He even shows off a few tricks before pocketing it.

* YouGottaHaveBlueHair: His hair is light blue.

* YouGottaHaveBlueHair: Her hair is green. Unnaturally green actually, since she dyed it to conceal her real appearance. Her hair is actually black, just like Aguri, to which she reverts in the ending.

'''The Main Characters''' | [[Characters/AssassinationClassroomClass3E Kunugigaoka Junior High School: Teachers and Students of Class 3-E]] | [[Characters/AssassinationClassroomMainBuilding Kunugigaoka Junior High School: Faculty and Students of the Main Building]] | [[Characters/AssassinationClassroomOthers Assassins and Other Characters]]]]-]]]

The primary characters of Class 3-E from Kunugigaoka Junior High School.\\\

[[folder:Koro-sensei]]
!!Koro-sensei
!!!'''Voiced by:''' Creator/MasayaOnosaka (Japanese, vomic), Creator/TomokazuSeki (Japanese, event anime and ''VideoGame/JStarsVictoryVS''), Creator/JunFukuyama (Japanese, TV anime), Creator/SonnyStrait (English), Creator/CarlosSegundo (Latin American Spanish)
!!!'''Portrayed by:''' Kazunari Ninomiya
[[quoteright:350:https://static.tvtropes.org/pmwiki/pub/images/korosensei.png]]
[[caption-width-right:350:[[labelnote:Click here to see his human form]]https://static.tvtropes.org/pmwiki/pub/images/human_koro.png[[/labelnote]]]]

->''"Let's have an assassination that will make people smile and puff out their chests with pride. Each and every one of you can do that. You are talented assassins with hidden strength. That is advice from your sensei, as a target."''

A mysterious octopus-like creature who was responsible for obliterating 70% of the Moon, leaving it a permanent crescent and also currently plans to destroy Earth after teaching the class for a year, and the homeroom teacher of Class 3-E of Kunugigaoka Junior High School.

* AbusiveParents: Of the emotional neglect variety. While he was "fair but firm" to his disciple as he raised him, Koro-sensei never once "looked at him", according to Aguri. To which his disciple realizes that he's nothing but a tool to his mentor, leading to his betrayal of him.
* TheAce: Not only is he an amazing teacher, but with his powers, he can flawlessly perform pretty much any task in flying colors, even the most implausible ones. [[spoiler:The yearbooks and personal guides he whipped up for his students before his death showcase this way better than words can.]]
* AffablyEvil: For a being who wants to destroy the world, Koro-sensei doesn't act like it. [[spoiler:Back when he was the original "Reaper", he was really polite and charming for a master assassin.]]
* AnimalMotif: The octopus. Like the animal, Koro-Sensei has several tentacles. He can also change his skin colour at will, which he uses both for communication and for camouflage.
* ApocalypseMaiden: [[spoiler:What he actually is, he WasOnceAMan, but antimatter experiments done on him turned him [[WhyAmITicking into a living bomb of world ending power.]]]]
* ArmorPiercingSlap: In Chapter 95 / Season 2 Episode 6 he slaps the entire class not only because they injured Matsukata during a LeParkour practice, but because they also tried to deflect responsibility. Karasuma does not report his action and pretends that nothing happened, even blaming himself for prematurely teaching them the skills without teaching them their responsibilities.
* TheAtoner: [[spoiler:For both his failure to protect Aguri, his past as a professional hitman, and his inability to properly guide his apprentice, who betrayed him to the government and assumed his "Reaper" persona, Koro-sensei has decided to spend his last days teaching her students at Class 3-E to honor her dying wish of helping them become better persons, even as he takes to heart her lessons about what it means to love and look after someone.]]
* BadassAdorable: He is so friendly, goofy and kind and often joins his students in their antics. Also no military in the world can kill this guy who also used to be the [[spoiler:[[WorldsBestWarrior world's greatest assassin]]]].
* BadassBookworm: Along with being a very knowledgeable educator, he makes quite a few nods to ''Shonen Jump'', including wearing a [[Manga/{{Naruto}} Leaf Village headband]] one time, and firing a giant slingshot using the [[Manga/OnePiece Gum Gum Slingshot]].
* BadassInANiceSuit: When he and [[spoiler:his disciple (the current "Reaper") did an infiltration mission -- and was subsequently betrayed by the latter.]]
* BadassTeacher: Koro-sensei is an extremely competent and protective teacher, who uses his inhuman abilities to teach and protect his charges. Trying to harm his students is an unwise move. [[spoiler: In the past he was this to the current Reaper/God of Death, although Koro sensei only viewed him as a tool to expand his own successes.]]
* BadLiar: He's bad at covering up his weaknesses. While this may be partially intentional, [[spoiler:it's also because as he became more of a tentacle monster he lost a great deal of his emotional control.]]
* BashBrothers: Together with Karasuma-sensei in the tag game.
--> "The strongest creature and the strongest human. [[ItMakesSenseInContext They're coming to attack us to give us more homework!!]]"
* BeautyToBeast: Was quite attractive when [[spoiler:he was still a human.]]
* BeingTorturedMakesYouEvil: [[spoiler:Briefly after he had broken out of his cell until Aguri [[CoolDownHug snapped him out of it]].]]
* BeCarefulWhatYouWishFor: When Koro-sensei was [[spoiler:still physically an ordinary human and being experimented upon, he admitted that he could have killed and escaped his captors on numerous occassions. However, because he was aware they were attempting to turn him into a weapon, he decided that it would be advantageous to him to attain the powers the experiments were giving him, and so he stuck around. Unfortunately, allowing the experiments to progress led to a point where the scientists deemed him too dangerous to live. His following escape attempt was fraught with so many deadly tactics to contain his power that it culminated in the death of Aguri, one of the people monitoring him who he'd grown to care for. In that moment he felt that his newly attained abilities were worthless]].
* BecauseYouWereNiceToMe: He became fond of [[spoiler:Aguri]] because she was the first person to show him kindness and teach him what it meant to look after someone.
* BerserkButton: The [[spoiler: anti-matter project]] is this for him. Not the victims, but the [[EvilGenius scientists]] involved, [[spoiler:[[ItsPersonal especially]] [[BigBad Yanagisawa/Shiro]]]]
* BewareTheNiceOnes: He's usually the nicest teacher you will ever meet, but when someone threatens his students you better watch out.
* BewareTheSillyOnes: Normally, he's goofy and fun-loving until his students are in danger or it's time to get serious.
* BigGood: Zigzagged. He is supposed to be Class 3-E's target because he supposedly will blow up Earth next March like he already did with the Moon. However, he is a ''great'' teacher and a kind, sensitive and respectful person who gets along with pretty much all his students and helps them and other people in every way he can, and his students' attempts on his life are more or less PlayedForLaughs. [[spoiler:Ultimately played completely straight once its revealed that he really didn't blow up the Moon.]]
* BigEater: Combined with SweetTooth. Or anything junk-foody.
* BirdsOfAFeather: [[spoiler:His friendship with Aguri stems from the fact that they are both troubled young adults living in abusive conditions.]]
* {{Bishonen}}: [[spoiler:His backstory reveals that he was actually quite the looker when he was still a human. Korosensei is capable of returning to his original form but never does it throughout the series.]]
* BizarreAlienBiology: Yes. Well, ish. He's born on Earth, he just doesn't look like it. From his [[ColorCodedForYourConvenience color-changing face]] to his [[SwissArmyAppendage multi-purpose tentacles]], with more quirks being revealed over time.
* BlitheSpirit: For a creature who intends to destroy the world, Koro-sensei is an expert in making people change their ways for the better. Karma, Irina and "Red Eye" are all examples people whose lives improved through his charisma and wisdom.
* BodyHorror: It looks pretty painful when he shoots himself to prove a point. [[spoiler:But especially his transformation looks outright terrifying looking at his arm being all messed up and [[{{Fingore}} fingers]] moving in all ways they shouldn't, and how he looks when he's rampaging throughout the facility he was tested in. One should be happy that he hid in the cave when the rest of his transformation happened.]]
* BunnyEarsLawyer: Moon/planet-killing, manga-drawing, supersonic, perverted, but really good teacher, anybody?
* BuxomIsBetter: Koro-sensei loves big breasts, and often takes a shine to Irina. [[spoiler:The flashback arc reveals that this originated from seeing Aguri in a tube-top that exposes her ample cleavage.]]
* CharacterDevelopment: Throughout the series, Koro-sensei undergoes a subtle, important shift in personality. Formerly [[spoiler:the original "Reaper", the greatest assassin in his time]], he slowly acclimated to the responsibilities of a teacher and to empathy itself, [[spoiler:only recently instilled in him by Aguri Yukimura, a gentle young teacher assigned to observe him during his confinement]]. This is justified, because [[spoiler:the "tentacles" have an emotionally reciprocal relationship to their host, being affected by and feeding into the host's emotional state. In late chapters, Koro-sensei states that he wanted to be "full of weaknesses, easy to get along with" and able to "touch even the weakest of things, protect them, and guide them"]]. This from a guy who responded to a reckless assassination attempt by threatening the students' families (though this is probably just a threat to make them not repeat another suicidal assassination).
* TheChessmaster: He's an extremely skilled strategist.
** For example, in the "Robbers and Cops" tag game, he and Karasuma are the cops and have to tag the class within an hour, but Koro-sensei has the given handicap to be in "jail" until the last minute. The students underestimate his extreme skills, and they realize that his handicap is even his advantage, since nobody can tag out the "arrested" students as long he's in the "jail".
** Even though Koro-sensei is easily tricked, he uses the moments where he's one-upped by his students to provide them with helpful advice. He teaches them how to evade Karasuma when they get out, implying that he might be deliberately falling for their tricks in order to give them more opportunities to gain experience and put his advice into action.
** This even goes back to his time as [[spoiler:a test subject in Yanagisawa's experiment. While the Grim Reaper is being experimented on, he manages to almost immediately understand the science behind the experiment. He then subtly alters the reported symptoms he experiences in order to trick Yanagisawa and guide the experiment along the path towards giving himself a more powerful form...all without the "genius scientist" even realizing it.]]
* CheshireCatGrin: His signature smile never moves, even when he's talking.
* ChivalrousPervert: He doesn't hide the fact that he loves women with big boobs, but he also defends Irina from a group of perverts who were harassing her and is an all-around good person, aside from that destroying the world issue. He has limits in his hobbies. He owns a stash of dirty magazines, but he insists he doesn't go farther than mailing the editors out of devotion when he is framed for going on a panty raid.
* ClarkKenting: When he wants to go out in public, he sticks a fake nose on his face, changes his skin color to a more normal tone, and puts on a wig. Amazingly, it works.
* ColorCodedEmotions: Physically so. Since Koro-sensei is almost always smiling, his emotions are read by his face's coloration and color pattern.
** Yellow: Normal
** Yellow with blushing cheeks: Very happy (usually, but not always, due to breasts)
** Green and yellow stripes: Mocking contempt
** Dark purple with X shape: Wrong answer face
** Orange with circle shape: Correct answer face (Two circles for perfect scores)
** Light blue: Sadness
** Dark blue: Shock[=/=]fear
** Red-orange: Angry
** Pitch black: Extremely angry
** Pink: Drowsy/relaxed
** White: Poker face[=/=]bewildered
** [[spoiler:Blindingly-white glow: All his emotions mixed together]]
* CombatTentacles: Comes with being octopoidal.
* CombinationAttack: [[spoiler:He combines all his emotional energies and experiences into one supercharged blast against the Reaper. Koro-sensei kills the Reaper and permanently paralyses Yanagisawa.]]
* CompellingVoice: He can whisper at high speeds in order to instill thoughts into people's heads. [[spoiler:He does this to the class during winter break to make sure they keep up with their studies despite their troubles concerning his past.]]
* CoolAndUnusualPunishment: He likes to punish failed assassination attempts by ridiculous means, such as dressing the would-be assassin in silly costumes, painting their nails, brushing their hair, placing strange objects on them, etc.
* CoolTeacher: He is a great teacher who is always there to motivate his students, protect them and have fun with them.
* {{Cosplay}}: In the anime, each episode ends with Koro-Sensei dressed up as the character with the most focus in the next episode, such as Karma or Irina. In the manga, each installment's title page has him in some kind of costume, some of which have generic themes but some of which are pop-culture characters (eg the class posed as in the iconic class photo image from the ''Literature/BattleRoyale'' franchise, with Koro-Sensei as Kitano from the film).
* CrazyPrepared: Dear Lord, but is he? The [[{{Doorstopper}} guidebooks]] he produces are just one (big) example.
** When he faces [[spoiler:Asano Sr. with grenade-trapped textbooks, he reveals he has memorized ''every'' textbook in Japan.]]
* DarkAndTroubledPast: [[spoiler:The man who became Koro-sensei was an orphan from a brutally corrupt slum in an [[PartsUnknown unnamed]] tropical country, who learned survival skills at a very young age until he became the legendary assassin simply known as the "Reaper", until his disciple sold him out to the Japanese government, which proceeded to conduct antimatter experiments that would turn him into a LivingWeapon. During this time he met Aguri, who helped him rediscover his humanity with her tales of her experiences as a middle-school teacher. Unfortunately, after an experiment to test the effects of aging on antimatter in a mouse resulted in the destruction of 70% of the Moon, head scientist Koutarou Yanagisawa decided to have him killed before he exploded next year. When Aguri warned him, he went on a despair-filled rampage in an attempt to escape, only to fail to protect Aguri from the tentacle of an antimatter container. With her last breath, she asks the heavily mutated Koro-sensei to look after her students.]]
* DeathSeeker: [[spoiler: Turns out, this is what the whole assassination arrangement with his students amounts to. Koro-sensei began his tenure with the knowledge that he was a ticking time bomb who would explode in a year, so he decided he wanted to instill as much knowledge as he could into the kids as he could in that time, ultimately desiring that he would meet his end at their hands before his expiry date. Initially, upon learning he was to die, Koro-sensei actually felt so much despair he was ready to let the world blow up with him, but Aguri's dying request that he teach her students ended up changing his outlook]].
* DefaceOfTheMoon: He blew up most of it prior to the story's beginning. [[spoiler:Except he actually didn't, it was a bluff to motivate his students. Although the real reason the moon blew up ''is'' connected to the same experiments that led to his powers]].
* DidntThinkThisThrough: Koro-sensei's habit of offering a handicap in assassinations as motivation for his students typically results in this reaction from him.
* DisappearsIntoLight: [[spoiler:He dissolves into countless particles of light after his students finally assassinate him.]]
* DramaPreservingHandicap: He isn't allowed to injure any of the students or staff as a condition to be allowed to teach to class 3-E. Never mind the human students, even [[spoiler:Itona]] wouldn't stand a chance against him if he were willing and able to retaliate.
** During the Assassination Island arc, the students' attempted assassination of him forces him to use his ultimate defense, which renders him unable to move for twenty-four hours - just as several of his students are affected with a deadly virus, with the only antidote in the hands of someone that wants to kill him. This forces Karasuma, Irina and the healthy students to risk their lives to get the antidote.
* DreadfulMusician: Weakness #27 -- He's tone deaf. His dreadful singing is powerful enough to shatter concrete.
* EldritchAbomination: Averted. Even though Koro-sensei looks like a freaky alien octopus, he states that he was born and raised on Earth. As what human, animal, vegetable, or mineral, it is anyone's guess.
* EtTuBrute: [[spoiler:Back when he was the "Reaper", he was sold out to the authorities by his disciple, who took on his name and reputation as his own.]]
** Invokes this trope in a hilarious way when he's accused of stealing the bras of big-breasted women in town; Isogai tries to defend him as a "normal pervert", but as he starts listing down Koro Sensei's perversions, even he tells him to just "turn himself in".
* EvenEvilHasStandards:
** Koro-sensei is not pleased when one of his students' collaborative attempt at killing him almost injures one of their own.
** When the students of another school kidnap Kayano and Kanzaki, he destroys said students for daring to touch ''his'' students.
** On a different note, he may be a pervert, but he'd never stoop as low as underwear theft and other such especially perverted acts.
* EvilLaugh: [[spoiler:As the "Reaper", when he overwhelms Koutarou Yanagisawa and his soldiers in his flashback story.]]
* EvilOverlord: His role in the ''Koro-Sensei Q!'' SpinOff. That said, he also acts as 3-E's teacher, much like in the original version.
* ExactWords: He's going to destroy the Earth come March, but until then, he's going to be Class E's teacher. [[spoiler:After all, [[YourDaysAreNumbered he's going to blow up on March 13]] unless he is killed first.]]
* ExcuseMeWhileIMultitask: When people try to kill Koro-sensei he's usually doing other things, such as meticulously trimming his attackers' eyebrows or giving a fighter jet a polish in midair. When helping his students study for the midterms by [[FlashStep flashing]] between them so fast he leaves an afterimage, he is also resting on a chair outside the classroom.
* ExplainingYourPowersToTheEnemy: Subverted. When he bothers to say anything at all, he only tells the basics, and often leaves out key details, like the fact that his mucus protects him from his weakness to water.
* ExtremeOmnivore: Aside from his habit of flying around the world to enjoy cuisines from different countries, he has been seen eating pens, tissues, knives, sodium hydroxide, aqua regia, plastic explosives, you name it.
* FaustianRebellion: [[spoiler:Before his first day of class, he uses his newly-gained powers to rip the scientists that caused them a collective new one.]]
* FlashStep: Koro-sensei has a top speed of Mach 20. During his introduction to Class 3-E, he easily dodges Karasuma while meticulously trimming his eyebrows. When attacked by state-of-the-art fighter jets, he gives them a midair waxing. When attacked by Isogai, Yada, Mimura, Maehara, Okano and Kataoka with knives, he disarms all of them, then replaces the knives with tulips without them noticing.
* AFormYouAreComfortableWith: The first chapter makes it clear that his current appearance is not his true form. Sans tentacles, his shadowy true form seems human-like. Averted at the revelation that [[spoiler:the "tentacles", referring to all the artificial components of his body, are altered by ''and alter'' the host's emotions. He began having minor but uncontrollable changes to his expression and limbs during the experiments, although his form remained stable until his RoaringRampageOfRevenge; it may be impossible for him to control his shape enough to play this trope straight.]]
* FragileSpeedster: By his own admission, he's so physically weak that it would take just one person grabbing each of his tentacles to pin him down. Good luck grabbing his tentacles, though.
* FreudianExcuse: [[spoiler:He became an assassin due to a horrific childhood, same as Irina.]]
* FridgeBrilliance: He goes through an InUniverse example when Karma discusses his plans for the future. At first, Koro-Sensei was iffy about a career as a bureaucrat being appropriate for someone like Karma, but, after Karma explained [[TheManBehindTheMan his logic behind his decision]], Koro-Sensei took it back, and conceded that it was perfect for him.
* FriendlyEnemy: To his students and his coworkers, he is polite, sociable, and encouraging, even as they try to kill him and he threatens to blow up the planet.
* GadgeteerGenius: Has extensive skill and knowledge with machines and electronics. He was able to upgrade Ritsu's capabilities for a relatively cheap sum of money and also built a custom motorcycle with a frame made of wood.
* GameFace: When his face turns pitch-black, it means he's ''very'' angry.
* GeniusBruiser: He is impossible to defeat in single combat, and he teaches every single subject at once without being challenged in any way.
* GeniusSweetTooth: He loves sweets and is usually seen eating them. He spends his salary as a teacher on them.
* GentleGiant: He's much larger than any human, but he's fairly harmless for a self-proclaimed world-destroying monster, even toward people trying to kill him. [[spoiler:He was originally a ruthless assassin, but became a friendly teacher to honor Aguri's last wish.]]
* GoOutWithASmile: Fully expects to do this. [[spoiler:And he does, smiling proudly to his class as he bids them a final farewell as they assassinate him.]]
* GoneHorriblyWrong: A super-powerful artificial creature, created to be the world's savior, now on course to destroy it in less than a year.
* GuileHero: For all his power, he almost always solves problems with trickery rather than brute force alone, often to the effect of bettering his opponents.
* HealingFactor: Koro-Sensei, amongst other abilities, has the power of regeneration. Even if he gets hit with AppliedPhlebotinum weapons, unless his body is almost completely destroyed, he'll recover in seconds.
* HeelRealization: After [[spoiler:Aguri's sacrifice]], he realized that for all his gifts and skills, he'd never tried to use them to help people, only to kill.
* HelpingWouldBeKillStealing: Though he may guide and coordinate them, he lets his students handle problems on their own whenever they're capable of it, which they usually are.
* HiroshimaAsAUnitOfMeasure: Every few chapters Koro-sensei is given a character introduction that includes one of these comparing to his ability to travel at mach 20. Some are fairly sensible ([[LudicrousPrecision 651.241]] times as fast as Usain Bolt's 100-meter dash) while others are ridiculous (133,333.33 times faster than the speed of falling sakura petals).
* ILetGwenStacyDie: [[spoiler:As he destroyed Yanagisawa's lab in his escape, Aguri tried to stop him with a CooldownHug, only for her to be fatally injured by the tentacle of an antimatter container. He became the teacher of Class 3-E to fulfill her last wish.]]
* IllKillYou: Koro-sensei threatens to kill the families of Class 3-E if any of them endanger one another during an assassination attempt, though from what is later learned about his personality, he was almost certainly bluffing.
* ImmuneToBullets: As Irina found out, he cannot be hurt by lead bullets, as the bullets literally melt inside his body.
* InformedAttribute: He is supposedly an evil monster who intends to destroy the world, and only hasn't done so yet because it would be boring... or so the narrative says. He actually acts like a kindly sage, helping everyone around him improve themselves. The dissonance is so extreme it's hard to imagine that it's not {{Foreshadowing}} some kind of reveal. And indeed, he's far from evil -- he just cannot help that [[spoiler:he will destroy the world if he's not killed, as the antimatter in his body will explode when he dies naturally]]. He wants to be killed and wants to help Class 3-E to save the world and [[spoiler:fulfill Aguri's dying wish.]]
* InvisibleStreaker: PlayedForLaughs; Koro-sensei uses his invisibility to avoid scaring a group of train passengers during a class trip, but his students point out that a random set of floating, disembodied clothing is just as unsettling.
* {{Invisibility}}: A rarely used ability, and his clothes and anything he's carrying will still be visible. He makes himself transparent by changing the color of his skin to match his surroundings like a chameleon.
* InvoluntaryShapeshifter: Koro-sensei transformed several times after drinking hazardous chemicals. In a more serious note, [[spoiler:after Aguri warned him of his impending death and that Yanagisawa was more than willing to kill him to preempt what he has done, he was not able to control his emotions and let the tentacles consume him.]]
* JerkWithAHeartOfGold: Koro-sensei wants to destroy the world and constantly teases his students for not being able to kill him, yet he always makes sure they get good grades and successes in life. As it turns out, [[spoiler:he had no intention of destroying the world, but the antimatter cells in his body will make him do so unless he is killed first, while his job as teacher was part of a promise he made with the dying Aguri to help her students become better people.]]
* KamehameHadouken: He learns to concentrate the energy from his Absolute Defense form into large beams.
* KiManipulation: Shown in chapter 84. [[spoiler:What's interesting is that ''he initially didn't know he could do that''; he learned it during the Island arc.]]
* KilledOffForReal: At the end of Chapter 177, [[spoiler:he's killed by his students before he can be killed by the government]].
* KryptoniteFactor: A rubbery material that is not described beyond being "special" and able to disrupt his cells on contact. It can be fashioned into knives, BB pellets or clothes, and is apparently available in abundance.
* LivingMoodRing: He can change his skin color and pattern to show his emotions, since he is [[PerpetualSmiler otherwise always smiling]].
* LivingWeapon: [[spoiler:Yanagisawa injected him with antimatter as part of experiments to turn him into Japan's OneManArmy. However, when a similar project on the effects of aging on a lab rat destroyed 70% of the Moon, Yanagisawa decided to hastily can the project, even if it means killing Koro-sensei, who only narrowly escaped through Aguri's warning and, ultimately, sacrifice.]]
* LovableSexManiac: He loves big-breasted women and enjoys reading porn magazines, yet he's still a funny and caring teacher.
* LoveRedeems: [[spoiler:He used to be the "Reaper", the greatest assassin in the world. When he met Aguri, her kindness made him understand what it meant to watch over others. He almost lost himself again after hearing he would die next year, but Aguri's death and her final wish made him decide to spend what little time he has teaching Class 3-E both as fulfillment of her dying wish and as his atonement.]]
* MajorInjuryUnderreaction: He casually blows or slices off his own tentacles, sometimes several at once. Supposedly this causes emotional disturbance that slows him down for a while afterwards, but that's still way less of a response than such injuries warrant. Of course, he can regrow his tentacles after a few seconds.
* MasterOfAll: [[spoiler:As the "Reaper", he's pretty much mastered almost every skill imaginable, in order to be a more effective assassin. He has complete knowledge of just about any subject, including a mastery of science that allows him to hijack Yanagisawa's experiment...while the "Reaper" himself is the one being experimented on.]]
* TheMatchmaker: A chapter has Koro-sensei pairing up the students into boy/girl pairs of his choosing to explore a cave in a poor attempt to cause some romantic tension between them. He even refers to the scheme as ''Couple Setup.'' Somewhat subverted in that he doesn't actually want them to get together as much as he wants juicy romantic gossip that he could poke fun at them for and write a novel about later.
* MeaningfulName: As mentioned under PunnyName, his nickname is a pun of "korosenai" ("unkillable" in Japanese) and "sensei".
* MultiformBalance: [[spoiler: His ultimate defense form makes him completely invulnerable. Not even the Anti-Sensei material will work; it will explode on contact with his shell. However, he is also immobile in this form for 24 hours, and he is afraid that somebody could send him on a rocket into outer space (though he admits that would be unrealistic, since sending him to space would take too long)]]. So while this form is truly unkillable, he has reason not to make regular use of it, and it doesn't make his molting ability redundant.
* MundaneUtility: This is practically the entire basis for his character. Koro-sensei boasts an enormous number of extraordinary abilities and he uses nearly every single one of them to be a better teacher. Able to fly at Mach 20? Use your speed to visit different countries during lunch breaks in order to sample local cuisine. Able to create dozens of visual clones through sheer speed? Use them to divide your attention to give every single student simultaneous one-on-one instruction. Able to regenerate from even severe injuries in a matter of seconds? Use the ability to remove limbs to motivate your students to perform better on the next test.
* MyGreatestFailure: [[spoiler:Aguri's death]] led to his HeelRealization and motivation to teach Class 3-E. [[spoiler:In the end, he also admits he was an improper teacher to his apprentice, who betrayed him and later became the second "Reaper".]]
* MyGreatestSecondChance: [[spoiler:When Aguri's younger sister Akari/Kayano is killed at the finale, Koro-sensei has the knowledge and preparation necessary to save her life this time. After stopping his rampage, he tells his ex-apprentice that were they to meet in the afterlife, he would RaiseHimRightThisTime.]]
* MysteriousPast: The beginning chapters already throw multiple question marks on his true identity, such as his motivations to become a schoolteacher and flashbacks to a dying woman who made him swear a promise. The latter half of the series ultimately reveals that [[spoiler:he was a test subject for an antimatter infusion experiment gone horribly wrong, and that the woman was Aguri, his first love, who encouraged him to spend his last days teaching Class 3-E.]]
* NeatFreak: Koro-Sensei has a bit of a hang-up with cleanliness. As mentioned before, he meticulously trimmed an assailant's eyebrows and waxed a fighter jet in midair.
* NiceHat: He ''always'' wears a mortarboard that never falls off... and also looks amusingly small.
* NighInvulnerability: He is able to withstand fire from multiple high-caliber machine guns at once. Apparently, the only things that can seriously harm him are the special anti-sensei material and [[spoiler:other beings similar to him, like Itona.]]
* NoSenseOfPersonalSpace: Getting really close to his students seems to a part of being a PsychologistTeacher. Just one example is wrapping up Sugino in his tentacles to evaluate the flexibility in the kid's joints.
* TheNoseKnows: He has an incredible sense of smell despite not having a proper nose. Some close-ups reveal nostrils almost identical to his eyes.
* NotMeThisTime:
** He's framed as being a PantyThief, but protests his innocence, insisting that, despite being a complete pervert, he'd never go ''that'' far. This turns out to be the truth.
** [[spoiler:Despite everything he ''did'' do during his time as the God of Death, he didn't actually blow up the moon, though it was the result of the same experiments that made him what he is now.]]
* NotTheFallThatKillsYou: Averted, though it involves sudden acceleration rather than deceleration. Koro-sensei cannot accelerate as quickly as he normally would if he has to catch or carry a normal human being because their bodies couldn't handle the physical stress.
* OctopoidAliens: He claims to be one at the beginning of the series [[spoiler:though this is revealed to not be his actual form.]]
* OmnicidalManiac: He plans to blow up the Earth, along with everyone living on it. [[spoiler:Eventually subverted, as it turns out that he has no control over the antimatter cells within him, which will explode on March 13 unless he is killed first.]]
* OneManArmy: He's so powerful entire fleets have been sent to go after him, mostly to no avail. [[spoiler:In fact, his backstory reveals that he brought a ten-year-long conflict at a country (presumably his homeland) to a standstill in a space of a week by killing two dozen members of the top brass.]]
* OnlyAFleshWound: Losing limbs may affect his speed, but having [[spoiler:two gaping holes shot through his head seems to have no effect on his ability to think at all.]]
* OnlyKnownByTheirNickname: When his students asked his name, he said he didn't have any name he could tell them, so they could call him whatever they wanted. Kayano then decided to call him "Koro-sensei". [[spoiler:He never had a real name, since he grew up on his own in the slums in an unnamed tropical country. Before becoming "Koro-sensei", he was known as "Reaper.]]
* OOCIsSeriousBusiness: When the goofy, fun-loving Koro-sensei becomes angry and breaks out his GameFace, prepare for this lighthearted manga to turn very serious, very quickly. He [[LampshadeHanging lampshades]] it after his first battle with [[spoiler:Itona]], when he turns embarrassed after one of his rare bursts of anger, lamenting that it will ruin his reputation as a gag character.
* PapaWolf: He is basically the father-figure that all of 3-E needs at this time in their lives, particularly those whoare not on good terms with their actual parents. Attack or bully his students and Koro-sensei will make sure you pay for it.
* {{Paparazzi}}: Where there's potential for spicy gossip (in particular ShipTease material), Koro-sensei is at hand to take notes and/or photographs.
* PartsUnknown: The name of the country where was born is never revealed. Given how horrible the place is described, it's probably not worth knowing about.
* PerpetualSmiler: He rarely breaks his constant smile, [[spoiler:even when he was being experimented on by Yanagisawa, or as he allows his students to give him a dignified death.]]
* ThePromise: Koro-sensei is teaching the students in his class as a promise he made to someone. As he once put it, teaching all of his students seriously is much more important to him than the end of the world. [[spoiler:He made the promise to Aguri Yukimura, Kayano's older sister and the class's previous homeroom teacher.]]
* PsychologistTeacher: Goes to extreme lengths to make sure that his students are able to resolve their own personal problems.
* PunnyName: Due to a [[NoNameGiven lack of a name]] at the beginning of the series, Kayano came up with Koro-sensei as a pun with the Japanese words "korosenai" and "sensei" ("unkillable teacher").
* RealMenWearPink: He knows how to groom eyebrows, and he does so quite impeccably.
* ReasonableAuthorityFigure: Koro-sensei may plan to blow up the world, but he's really undestanding as a teacher. If a student fails an assassination attempt, he'll sit down with them and discuss how they can do better next time in a constructive manner.
* RedBaron: When he was human, he was known as [[spoiler:the "Reaper", the world's greatest assassin.]]
* RedEyesTakeWarning: When his face changes to black he drops all his usual goofy characteristics and becomes seriously menacing.
* RequiredSecondaryPowers: Flying at Mach 20 requires a few other traits to work properly, such as hardening and streamlining of his body so that he can withstand the whiplash and G forces. Also, he has to use his tentacles to screen Nagisa and Karma when they travel with him so they don't get pelted by high speed dust.
* RememberWhenYouBlewUpASun: He brags about being the one who blew up the Moon. [[spoiler:Except he actually didn't.]]
* ScreamsLikeALittleGirl: His voice gets quite high when he's splashed with water.
* SecretlyDying: In Chapter 133 he reveals [[spoiler:he's going to die anyway on March 13 even if no one manages to assassinate him.]]
* SelfDuplication: He can move so fast he can make selectively tangible afterimages. Chapter 12 shows him making one for every student in the class to personally focus on their weak subjects. He even leaves one outside to rest from all that work.
* ShipperOnDeck: He, and the rest of Class 3-E, ship Karasuma/Irina.
* SignatureLaugh: "Nurufufufu."
* SilentScapegoat: [[spoiler:He isn't the one who blew up the Moon as he claims – it was a lab rat transplanted with antimatter generating cells, sent on a satellite to the Moon as part of an experiment to test the effects of aging on the cells which had GoneHorriblyWrong.]]
* SlasherSmile: His GameFace color: Pitch Black.
* SlaveToPR: If there is one thing he will avoid more than death, it is disspointing his students. He wants them to see him as a trustworthy individual who is sincere in his desire to teach them to succeed in life (and in killing him). This is exploited by all those who want to kill him (including his students) such as when [[spoiler: Shiro framed him as an underwear thief, and he ran headlong into a trap to clear his name after seeing how disappointed his students were in him]].
* SmugSuper: Well, yes. No chapter is missing without him boasting that he's unkillable. He even has a smug face, where several green stripes cross his face.
* StarCrossedLovers: With [[spoiler:Aguri Yukimura, Akari/Kaede Kayano's older sister and previous homeroom teacher of Class 3-E.]]
* StealthMentor: Many times, Koro-sensei's lessons have multiple reasons behind them, always working to help his students grow as assassins and people.
* StoneWall: His Ultimate Defense technique takes this to an extreme: [[spoiler:He releases most of the energy and matter in his body in an explosion that blows away nearby enemies, then condenses said energy and matter into a ball-shaped barrier around him. This makes him absolutely invulnerable, but leaves him as a talking head for 24 hours.]]
* StreetUrchin: [[spoiler:As a child, he grew up on his own in a brutally corrupt slum in an unnamed tropical country. Due to his violent background, he became an assassin eventually known as "Reaper".]]
* SuperDrowningSkills: Because his body is sponge-like, it absorbs water quickly, weighing him down on water.
* SuperSpeed: Koro-sensei, as previously mentioned, can move at Mach 20. He eats shaved ice he personally gathers from the North Pole. He eats Chinese food on his lunch break... in China.
* SuspiciouslySpecificDenial: In chapter 43.
-->'''Koro-sensei:''' "...I mean, I just don't really feel like [[spoiler:swimming]]. And it's not like [[spoiler:my tentacles get all bloated underwater and I can't move]] or anything."
* TallDarkAndHandsome: [[spoiler:When he was a human, he was a really handsome black-haired man.]]
* TentacleHair: [[spoiler:Before fully mutating into his current appearance, upon finding out the scientists that experimented on him intend to kill him, Koro-sensei suddenly manifests tentacles all over his body, predominantly on his head, completely replacing his black hair with long, white tendrils]].
* TerribleArtist: One of his minor weaknesses, he can only do simple art. And he still challenges Sugaya, the best artist in class, to making henna tattoos.
* ThisLoserIsYou: The Season 2 Premier, and Chapters 74-76, in which Koro-Sensei attempts to play ShipperOnDeck for his students, ends up being a TakeThat to real life shippers. His students end up finding it creepy that he's so interested in trying to pair off a bunch of kids.
* TogetherInDeath: [[spoiler:In the epilogue, Kayano imagines that somewhere he and Aguri are now watching over Class 3-E even after seven years.]]
* TombstoneTeeth: Koro-sensei sports a brick-toothed grin that only adds to his cute-but-creepy Smiley Face-with-tentacles appearance, and is the cherry on top of him being a borderline EldritchAbomination with enough power to destroy the planet. When he gets angry, however, his teeth turn into fangs. [[spoiler:Even when he was human, he'd sport a brick-toothed grin for comical effect when he was being perverted.]]
* TooPowerfulToLive: He is this to the entire world. [[spoiler:Even though his chances of actually destroying the world are less than 1%, world governments refuse to even consider the possibility of letting him live. Even discounting that, his abilities are so game-breaking he can do whatever he wants, and no one would be able to stop him. This is why all later examples of beings with his power were deliberately given either critical weaknesses or shortened lifespans.]]
* TragicKeepsake: [[spoiler:His necktie was a birthday gift from Aguri Yukimura, the woman he loved and who gave him a birthday.]]
* TragicMonster: [[spoiler:He's about to destroy the Earth just like he did with the Moon... and it's not completely of his own free will. For one, he's actually taking the blame for an antimatter-infused lab rat destroying the Moon, while the same cells in his body have turned him into a walking time bomb.]]
* TranquilFury: When [[spoiler:Kayano was impaled by Number Two, he barely uttered a word or raised his voice despite his absolute fury. He simply concentrated all his power into one final, devastating attack and made short work of Shiro and Number Two. It's less tranquil in the anime, where he emits a roar of uncontrollable rage for several seconds as he turns white.]]
* VillainProtagonist: He destroyed the Moon and plans on doing the same to Earth in a year. Until then, he's going to fulfill a promise to be a teacher, and he's going to do it perfectly. As such, based on what we know, the only reason people targeting him can be considered bad guys is because they don't always care about not putting Class 3-E in danger. [[spoiler:Ultimately, he proves himself GoodAllAlong, when it was revealed that he actually didn't destroy the Moon (it was a lab rat), but he took the blame anyway, while teaching Class 3-E was him fulfilling his promise to the dying Aguri, and he actually [[DeathSeeker wants to be killed]] before the antimatter cells inside his body destroy the world.]]
* WasOnceAMan: [[spoiler:He originally was a fearsome assassin known as the "Reaper", until some government experiments turned him into what he is now.]]
* WeaksauceWeakness:
** Weak to water. Specifically, his body is sponge-like. Even a day with high humidity causes him to swell up comically. If he actually found himself immersed in water it would certainly get much worse and slow him down significantly. [[spoiler:The mucus his skin releases can protect him from it, but it can be depleted.]]
** The anti-sensei weapons are basically his Kryptonite, which is notable as it's completely harmless to normal humans.
* WhatCouldHaveBeen: InUniverse, [[spoiler:Aguri thinks that had he not grown up in a WretchedHive, most of his personality quirks or weaknesses (other than his inability to swim) would've likely been expressed as a human being as well.]]
* WhyAmITicking: [[spoiler:The real reason he will destroy Earth on March 13 is because the antimatter-generating cells Shiro/Yanagisawa put in his body will make him explode.]]
* WillfullyWeak: [[spoiler:He asked his tentacles to make him weak, so he could become a teacher that could easily get along with others and protect his students.]]
* WorldsBestWarrior: He held that title alongside his disciple as the greatest assassin. After the transformation, he became the WorldsStrongestMan, but he wanted to be killed by his students.
* YourDaysAreNumbered: [[spoiler:He is going to die in upcoming March 13 anyway, since his anti-matter generating cells will make him explode. Actually averted, in that the chance of instability and thus antimatter explosion decreases with increasing body size. For Koro-sensei, who is at least twice as large as a fully-grown human, the odds were ridiculously small to begin with, but drinking a certain chemical mix would reduce the chances to ''less than 1%'' (and [[ChekhovsGun that was the very formula that made his body as liquid]] way back in the beginning chapters of the series). The danger was ''never there'', but world governments aren't willing to dismiss that 1%.]]
----
[[/folder]]

[[folder:Nagisa Shiota]]
!!!'''Voiced by''': Creator/NozomiYamamoto (Japanese, vomic), Creator/NaoTouyama (Japanese, event anime), Creator/MaiFuchigami (Japanese, TV anime), Creator/LindsaySeidel (English), María José Moreno (Latin American Spanish)
!!!'''Portrayed by''': Ryosuke Yamada
[[quoteright:200:https://static.tvtropes.org/pmwiki/pub/images/nagisa_0.png]]

->''"Like you've got the balls to try [killing someone]. Go right ahead."''

The most often seen student, and the main perspective character. He fell into Class 3-E at the end of the previous year due to poor grades. Mild-mannered, cautious and relatively weak (not to mention rather effeminate), he prefers to observe and collect data on Koro-sensei's weaknesses rather than participate in assassination attempts. Despite that, or perhaps because of it, he is considered to be one of the best assassins-in-training in the class.\\\

5th best marksmanship, boys' side.
----

-->'''Hiroto:''' He's scary...
-->'''Meg:''' Even more terrifying that he doesn't even realize it...
-->''Everyone's beginning to see how dangerous he is.''

* TheNarrator: Most of the anime and manga is narrated by Nagisa.

* EvenEvilHasStandards: Koro-sensei is not pleased when one of his students' collaborative attempt at killing him almost injures one of their own.

* BigGood: Zigzagged. He is supposed to be Class 3-E's target because he supposedly will blow up Earth next March like he already did with the Moon. However, he is a ''great'' teacher and a kind, sensitive and respectful person who gets along with pretty much all his students and helps them and other people in every way he can, and his students' attempts on his life are more or less PlayedForLaughs. [[spoiler:Ultimately the "Big Bad" part is subverted when it turns out that he really didn't blow up the Moon, while he is also actually an involuntary time bomb due to the antimatter cells implanted inside his body.]]

* CharacterizationMarchesOn: Throughout the series, Koro-sensei undergoes a subtle, important shift in personality. Formerly [[spoiler:the original "Reaper", the greatest assassin in his time]], he slowly acclimated to the responsibilities of a teacher and to empathy itself, [[spoiler:only recently instilled in him by Aguri Yukimura, a gentle young teacher assigned to observe him during his confinement]]. This is justified, because [[spoiler:the "tentacles" have an emotionally reciprocal relationship to their host, being affected by and feeding into the host's emotional state. In late chapters, Koro-sensei states that he wanted to be "full of weaknesses, easy to get along with" and able to "touch even the weakest of things, protect them, and guide them"]]. This from a guy who responded to a reckless assassination attempt by threatening the students' families (though this is probably just a threat to make them not repeat another suicidal assassination).

* PartsUnknown: The name of the country he was born in is never revealed. Given how horrible the place is described, it's probably not worth knowing about.

* DarkAndTroubledPast: [[spoiler:The man who became Koro-sensei was an orphan from a brutally corrupt slum in an unnamed tropical country, who learned survival skills at a very young age until he became the legendary assassin simply known as the "Reaper", until his disciple sold him out to the Japanese government, which proceeded to conduct antimatter experiments that would turn him into a LivingWeapon. During this time he met Aguri, who helped him rediscover his humanity with her tales of her experiences as a middle-school teacher. Unfortunately, after an experiment to test the effects of aging on antimatter in a mouse resulted in the destruction of 70% of the Moon, head scientist Koutarou Yanagisawa decided to have him killed before he exploded next year. When Aguri warned him, he went on a despair-filled rampage in an attempt to escape, only to fail to protect Aguri from the tentacle of an antimatter container. With her last breath, she asks the heavily mutated Koro-sensei to look after her students.]]

** [[spoiler:Blindingly-white glow: ''Pissed beyond all reason'']]

* TheNoseKnows: He has an incredible sense of smell despite not having a proper nose.

* SweetTooth: He loves sweets and is usually seen eating them. He spends his salary as a teacher on them.

* KnightOfCerebus: An odd example because she was present from the very begining, but the reveal of her true nature is a major WhamEpisode that makes the whole class rethink everything about her and leads directly into even more major reveals about Koro-sensei's past.

* BullyHunter: It was this hobby of his that landed him in Class 3-E when he beat up a top-ranking student in defense of a member of said class. He still gets massive kick out of seeking out and harassing individuals with nasty personalities.

* ManiacTongue: Karma's CharacterTic. He '''LOVES''' to stick his tongue out every time he's being playful, it's like his own version of the SillyMeGesture.

** Even [[Yanagisawa laughed about how she died in front of him like her sister did.

* ImpaledWithExtremePrejudice: Happens to her during the final battle, courtesy of the second "Reaper". Koro-sensei resurrects her using his newly-learned medical knowledge.]]

* ArtifactAlias: Kaede Kayano isn't her real name, but she asks her friends to keep calling her that as a nickname even after her real identity is revealed, since she came to like it.]]

* AesopAmnesia: Even after learning (in the flashback arc) that dishonesty is a painful and ineffective way of dealing with life's problems, she still instinctively lies to get herself out of awkward situations. This is actually a bit of FridgeBrilliance: Something like that can't be handled so quickly, especially when it's something of a "bad habit".

* ChildProdigy: [[spoiler: He has a natural gift for assassination, able to note weakpoints at a glance and conceal his blodlust when attacking.]]

* ApocalypseMaiden:[[spoiler: What he actually is, he WasOnceAMan, but antimatter experiments done on him turned him [[WhyAmITicking into a living bomb of world ending power.]]]]

* HellishPupils: His pupils change to [[AnimalEyes ones similar to snakes']] on some rare occasions. Especially before he started taunting Nagisa relentlessly. See also YellowEyesOfSneakiness.

* ALessonInDefeat: [[spoiler:His scores slip during the first term finals]] because he was arrogant about his intelligence and didn't study hard enough to succeed with the increased difficulty. Fortunately, he takes the lesson to heart, and starts working much harder from then on.

* MrViceGuy: Karma displays a ''wide'' variety of vices or flaws, such as slyness, arrogance, recklessness, and bloodlust. He learns how to subdue most of them, but some, like cunning, remained with him. See also SociopathicHero below.

All spoilers in Kaede Kayano's entries are unmarked. Administrivia/YouHaveBeenWarned!

* * DavidVersusGoliath: His fight with [[spoiler:Takaoka]] is one.