Assassination Classroom Episode 21 Recap & Characters (Spoiler-Free)

Spoiler-free episode guide for Assassination Classroom: recap and characters up to Episode 21 — nothing past this episode.

Episode Summary

XX Time

In the hotel's concert hall, Korosensei directs the hidden class while Chiba and Hayami disarm the hitman Gastro. Karasuma then takes out a guard on the top floor, and the class finds Akira Takaoka, the mastermind behind their illness, who forces Nagisa to kneel and apologise on the helipad before destroying the antidote vials. Overcome by rage and despair, Nagisa picks up Takaoka's knife and vows to kill him.

Concert hall standoff with Gastro
Gastro blocks the class in the hotel's soundproof concert hall and trades live fire with Hayami. Korosensei, placed in the front row, directs the hidden students with shuffling orders; after a decoy made by Sugaya draws Gastro's fire, Chiba's shot drops a stage light on him, Hayami shoots the revolver from his hand, and the boys tie him up.
Top floor advance and mastermind reveal
Karasuma, half recovered, subdues a lone guard, and the class reaches the mastermind's room, where the antidote sits in a briefcase rigged with explosives. The man throws spare detonators into the air and is revealed as Akira Takaoka, the man behind the illness.
Helipad humiliation and antidote destruction
Takaoka forces Nagisa to kneel and apologise, then blows up the briefcase holding the antidote vials, leaving the group helpless and Nagisa resolved to kill him.

Recent Timeline

Failed hut assassination and extortion call (Episode 18)
The class's all-out attack at the island hut fails when Korosensei shrinks into an unbreakable crystal sphere that leaves him immobile for a day. Back at the resort half the class falls ill with an artificial virus, and a caller offers the only antidote in exchange for Korosensei, to be delivered to a mountaintop hotel within an hour.
Lobby distraction and hitman ambush (Episode 19)
Irina feigns being a tipsy pianist, using music and body language to draw the lobby guards away and give the class twenty minutes to slip upstairs unnoticed.
A hired hitman posing as a guest then releases a gas cloud. Karasuma inhales a little but kicks the hitman unconscious before collapsing himself, leaving the students to press on without their teachers.
Karma defeats Grip in hotel duel (Episode 20)
Karma goads Grip into a one-on-one fight, dodges his attacks and, when Grip springs a paralysing gas on him, counters with an unused spray he had pocketed from the fallen Smog. Grip tries a hidden blade, which Karma knocks away before calling Terasaka to help pin him down, and Grip is bound with duct tape.
Gastro subdued and Takaoka unmasked (Episode 21)
Gastro senses the hidden class without seeing them, but Korosensei distracts him while Chiba and Hayami fire; Hayami's second shot knocks the revolver from his hand, and the boys tie him up.
When the class reaches the mastermind's room, Takaoka throws several remote detonators into the air and is revealed as the man behind the classmates' illness, a scarred and unhinged former soldier.
Antidote destroyed on helipad (Episode 21)
On the helipad, Takaoka forces Nagisa to kneel and apologise, then blows up the briefcase of antidote vials. The sick classmates are left without a cure, and Nagisa, enraged, picks up the knife Takaoka had dropped.

Character Graph

Korosensei

Class 3-E teacher · Super creature

Super creature who destroyed 70 percent of the moon, vows to destroy Earth next March, and teaches Class 3-E. Placed in the front row of the concert hall, he directs the hidden students with shuffling orders and code names, and steadies Chiba and Hayami before their shots.

Assassination target
He offered to teach Class 3-E himself and the government reluctantly agreed; the students must kill him by March for a 10 billion yen bounty.

Chiba (Mentor, Affinity)
Student he reassures that he does not have to carry the pressure alone.
Nagisa Shiota (Mentor, Mixed)
Student whom Takaoka singles out for revenge on the helipad.

Nagisa Shiota (Nagisa)

Class 3-E student

Class 3-E student who keeps notes on Korosensei's habits and weaknesses. On the helipad Takaoka makes him kneel and apologise for their earlier fight, then blows up the antidote in front of him; consumed by rage, Nagisa picks up Takaoka's knife and vows to kill him.

Korosensei (Mentor, Mixed)
His homeroom teacher and assassination target; Nagisa respects him as a good teacher while aiming to kill him.
Akira Takaoka (Other, Hostility)
Former PE teacher he beat with a real knife, who now singles him out for revenge.
Ryoma Terasaka (Colleague, Affinity)
Classmate he notices is feverish with the virus but hiding it.

Tadaomi Karasuma

Ministry of Defense · PE teacher

Ministry of Defense officer who teaches PE to Class 3-E and trains the students in assassination. Half recovered from the gas, he chokes out a guard on the top floor and unmasks the mastermind as Takaoka, a Ministry insider who vanished with the ministry's secret assassination funds.

Korosensei (Pact, Hostility)
The target he must see killed; the creature offered to teach Class 3-E himself and the government reluctantly accepted.
Akira Takaoka (Colleague, Hostility)
Former colleague he exposes as the mastermind.

Karma Akabane

Class 3-E student

Class 3-E student with a sharp mind and a taste for mischief, who returned from a school suspension and was the first to wound Korosensei. He mocks Takaoka for picking on Nagisa because of the size difference and offers to take him on instead.

Akira Takaoka (Other, Hostility)
Mastermind he taunts for picking on Nagisa.
Nagisa Shiota (Colleague, Affinity)
Close friend and classmate.

Kayano

Class 3-E student

Class 3-E student and Nagisa's close friend. She begs Nagisa not to go up to the helipad alone when Takaoka summons him, and learns that Takaoka had meant to use her to seal Korosensei in cement.

Nagisa Shiota (Colleague, Affinity)
Close friend and classmate.

Ryoma Terasaka

Class 3-E student

Class 3-E student who used to throw his weight around and joined the class as an ally after Shiro used him in the pool trap. Hiding that he too has caught the virus, he presses on with the class, and tells Takaoka that Nagisa beat him fair and square under his own rules.

Nagisa Shiota (Colleague, Affinity)
Classmate who notices his fever; Terasaka makes him keep quiet.

Chiba

Class 3-E student · Sniper

Class 3-E student whom Karasuma presented to Lovro as an unrivalled long-range sniper. Kept hidden on Korosensei's orders, he waits until a decoy made by Sugaya draws Gastro's fire, then shoots the stage light's fitting so the light falls on him.

Specialty
Long-range sniping

Rinka Hayami (Colleague, Affinity)
Fellow sniper who follows up his shot.

Rinka Hayami

Class 3-E student · Sniper

Class 3-E student praised for precise hands and dynamic vision, excellent at hitting moving targets. Her first shot misses Gastro's gun and draws his return fire, but her second knocks the revolver from his hand.

Specialty
Hitting moving targets

Chiba (Colleague, Affinity)
Fellow sniper whose shot set up hers.

Gastro

Hitman

Hitman and former soldier with a habit of tasting his guns. In the soundproof concert hall he trades live fire with the class, but Korosensei's shuffling orders confuse him, Chiba and Hayami disarm him, and the boys tie him up.

Akira Takaoka (Pact, Neutral)
Employer who hired him.

Akira Takaoka (Takaoka)

Former Ministry of Defense · Former soldier

Former elite-corps instructor from the Ministry of Defense who briefly took over Class 3-E's PE and was beaten by Nagisa in a real-knife match. Revealed as the mastermind who hired the hitmen and poisoned the class, he wants the bounty and revenge, and blows up the antidote after making Nagisa kneel on the helipad.

Original plan
He meant to make Kayano hold Korosensei in a bathtub of anti-sensei BBs and seal them in cement, so that Korosensei could escape only by blowing up a student.

Nagisa Shiota (Hierarchy, Hostility)
Student he blames for his humiliation; he forces him to kneel and apologise, then destroys the antidote.
Tadaomi Karasuma (Colleague, Hostility)
Former colleague who exposes him.

World Memo

Crescent moon and the destruction of Earth
At the start of the students' third year the moon suddenly exploded into a permanent crescent. The creature responsible has declared that he will destroy Earth next March in the same way, a standing threat that frames the assassination.
Government-sanctioned assassination and reward
The government reluctantly accepted the creature's own offer to teach Class 3-E on condition that he harms no students, and secretly tasked the class with killing him, since public knowledge would cause global panic. A successful assassination is rewarded with 10 billion yen.
Anti-sensei weapons
The government developed anti-sensei BBs and knives that are harmless to humans but break down the creature's cells, and supplies them to the students.
Class E's standing and the school system
Kunugigaoka's Class E is sent every day to an isolated mountaintop campus and discriminated against as the lowest-ranked class, nicknamed the E-as-in-End Class. The chairman deliberately keeps it at the bottom in grades and treatment so that fear of falling into it drives the other students. To escape, a student must rank in the top 50 of the 186 third-years and get permission from their former homeroom teacher.
The mountaintop hotel's secrecy
The hotel at the top of the island's mountain is known to house questionable guests and host illegal meetings through contacts with someone in the government, and its privacy policy blocks even government inquiry into guests.
Anti-terror stair layout
The hotel's stairs are deliberately placed apart from one another, a layout planned to counter terrorist takeovers, and the elevators cannot be used without a separate IC card for each floor.
Soundproof concert hall
The hotel's concert hall is fully soundproof, so gunshots fired inside cannot be heard outside.

Clue Board

Real name unknown (Episode 1)
Korosensei says he has no name worth giving and lets the class pick one; Kayano comes up with 'Korosensei'. His real name remains unknown.
Woman in the ruins (Episode 1)
In a brief flashback Korosensei holds a bleeding woman in a ruined building; she tells him that with those tentacles he would surely become a wonderful teacher. Who she is remains unknown.
A promise to someone (Episode 2)
Korosensei tells Nagisa he became their teacher to keep a promise he made to someone. He does not say who.
Unknown motive for the deal (Episode 1)
Korosensei himself offered to teach Class 3-E, and the government reluctantly agreed on condition that he never harms the students, but no one knows why he wants to teach. His motive remains unexplained.
Vague answer on the punishment (Episode 4)
Nagisa grows suspicious after Korosensei's punishment of Irina, and Korosensei gives only a vague answer when asked for clarification, leaving the reason open.
The chairman's words (Episode 6)
The chairman, briefed by the Ministry of Defense, calls Korosensei a sad being who meant to become the world's savior but ended up a great evil that will destroy it. What else he knows is not shown.
Korosensei's past romances (Episode 8)
Karasuma started to ask whether Korosensei's romances dated from a time when he had two arms and two legs, then let it drop. What Korosensei used to look like is still unexplained.
Shiro and Itona's score over the moon (Episode 10)
The night before Itona's arrival, Shiro told him that Korosensei is his brother and will be his teacher from tomorrow, then said they would go settle the score over the moon. What the two hold against Korosensei over the moon is still unexplained.
Reason for current form and teaching Class E (Episode 11)
Students ask why Korosensei takes his current form and why he teaches Class E. He answers seriously that they must earn these answers by trying to kill him, so the reason remains hidden.
Claimed brotherhood with Itona (Episode 11)
Shiro insists Itona and Korosensei are brothers despite different parents and upbringings, and the fight is presented as proof. Korosensei says he was raised as an only child and does not know what Itona means. The relation is unresolved.
Source of Itona's tentacles (Episode 11)
Itona has tentacles like Korosensei's growing from his hair. Korosensei demands to know where they came from, but Shiro refuses to answer, so the origin stays unexplained.
Another critical weakness of Korosensei (Episode 14)
A further weakness of Korosensei surfaced during the pool assault, described as far more important than his inability to swim. The class did not realize it at the time, and its nature is not revealed.
Shinigami, the world's best assassin (Episode 17)
Lovro says the best assassin in the world is known only as the Shinigami (God of Death), and that targets who cannot be assassinated eventually encounter him; his identity is not revealed.
Three unreachable assassins (Episode 17)
Lovro had told Karasuma that three promising assassins could no longer be contacted. At the hotel Karasuma reveals that one more person had gone missing besides those three hitmen: Takaoka, who hired them for his plot.
Lovro's surefire killing technique (Episode 17)
Lovro begins to tell Nagisa of a surefire killing technique, but the explanation is cut off, leaving the technique unrevealed.
Caller behind the illness (Episode 18)
The caller who claimed to hold the only antidote turns out to be Akira Takaoka, who wants the bounty and revenge on the class; on the helipad he destroys the antidote in front of Nagisa.
Poisoner identified as the butler guest (Episode 19)
Fuwa deduces the hotel guest who triggered the gas is the butler who served drinks, the poisoner, because the drinks were the only shared item when the class was together and the students who skipped dinner still fell ill; the man neither confirms nor denies it.
Karasuma's recognition of the guards (Episode 20)
Karasuma seems to recognise the two unconscious guards up close; why has not yet been explained.

Deduction Board

Facts

Artificial contagious virus
The caller states the illness is an artificial contagious virus that kills within a week if untreated.
Caller unmasked as Takaoka
The man behind the call and the virus is Akira Takaoka, a Ministry of Defense insider who vanished with the ministry's secret assassination funds.
Antidote destroyed
Takaoka blows up the briefcase containing the antidote vials, so the only cure is gone

Evidence

Private number call to Karasuma
Karasuma receives the call from a private number during the illness outbreak.
Demand for Korosensei
The caller offers to trade the antidote for Korosensei, requiring the two smallest students to deliver him to a mountain-top hotel within an hour, with no lateness or outside contact.
Class watches helplessly
The class watches the briefcase explode and Nagisa looks at Terasaka, who is struggling to remain standing

Inferences

Mastermind is no professional
Korosensei notes the mastermind misuses his hitmen as guards, which leads Karasuma to conclude he is not an assassin himself.
Drinks were spiked with poison
Fuwa concludes the drinks served on arrival were spiked with poison
Abusive training method
Akira Takaoka's recruit training appears to involve physical abuse

Suspicions

He is the poisoner
Fuwa suspects the butler-guest poisoned the class; he neither confirmed nor denied it
Grip will use any means
Grip springs gas in the middle of a bare-handed duel, saying nothing is unfair in assassination, which suggests he will use any means to win.
Missing hitmen hired by Takaoka
Karasuma says that besides the three hitmen who had gone out of contact, one more person had disappeared: Takaoka, suggesting the hitmen at the hotel are the missing assassins Lovro mentioned.

Battle Record

Takaoka's extortion standoff escalates on the helipad: he forces Nagisa to kneel, then destroys the antidote vials, leaving the class without a cure.

Karma vs Grip hotel duel

Hotel hand-to-hand duel · Episode 20

Location: Hotel view corridor

Trigger: Karma goads Grip into fighting him instead of calling for reinforcements

Sides

Class 3-E — Student: Karma Akabane
Assassin — Hitman: Grip

Outcome: Karma wins; Grip is disarmed and bound with duct tape

Aftermath

Karma reveals he had pocketed an unused gas spray from the fallen Smog

Concert hall standoff with Gastro

Hidden class versus hitman · Episodes 20–21

Location: Hotel concert hall

Trigger: Gastro blocks the class's way forward

Class E versus hitman

Class E — combatants: Hayami, Chiba, Korosensei
Gastro — hitman: Gastro

Outcome: Gastro disarmed and tied up by the boys

Aftermath

Class congratulates itself; Karasuma notes their faces look more like junior high students than before the fight

Hotel antidote extortion standoff

Takaoka's humiliation demand · Episode 18– (Ongoing)

Location: Helipad on the hotel rooftop

Trigger: Takaoka withholds the antidote and demands a fight and an apology

Class E versus Takaoka

Class E — students: Nagisa, Terasaka, Kayano
Takaoka — mastermind: Akira Takaoka

Outcome: Antidote vials destroyed; standoff unresolved with Nagisa picking up a knife

Aftermath

Takaoka destroys the stairs so no one can interfere
The sick classmates' only cure is lost

Ability Table

User	Ability	Description
Korosensei	Mach 20 speed	Can fly and move at up to Mach 20, fast enough to dodge a whole classroom's volley of BBs and to tutor each student at once with afterimage clones.
Korosensei	Tentacle regeneration	A tentacle destroyed by anti-sensei weapons grows back within seconds, though regrowing it uses up a good deal of stamina.
Korosensei	Monthly skin shedding	Once a month he can shed his skin and use it as a shield. Shedding drains more energy than it looks and slows him afterward; against Itona he escaped by shedding and later wrapped Itona in the shed skin.
Korosensei	Keen sense of smell	Has a keen nose: he can sniff out sweets from far away and caught the unfamiliar men hidden in the storage shed by their body odor.
Korosensei	Mucus	Secretes a sticky mucus that caught a sniper's bullet on oil-blotting paper and doubles as bath foam that lifts away dirt.
Korosensei	Crystal sphere defense form	Shrinks his body and seals it in a tiny crystal of condensed energy that nothing, not even a nuclear blast, can damage. The crystal breaks down naturally after about a day, during which he cannot move at all; even if sealed in anti-sensei material, he can blast his surroundings away when he returns to normal.
Nagisa Shiota	Natural assassin's talent	Small and easy to overlook, he can walk up to a target holding a real knife as calmly as if walking to school. In the real-knife challenge he slipped behind Takaoka, froze him with a feinted neck slash and pinned him down, and Karasuma recognized him as a natural-born assassin. Lovro also senses the talent and starts telling him of a surefire killing technique.
Ryoma Terasaka	Stun rod electrocution	Stun rods that electrocute a target on contact. Terasaka bought them with some extra money he had come into, meaning to try them on Korosensei, and used them with Yoshida to knock out two guards.
Tadaomi Karasuma	Five knife strikes per second	Can strike a target five times with a knife in a single second.
Ritsu	Adaptive fixed artillery fire	Fires repeated volleys from her anti-sensei guns at Korosensei while calculating her chance of killing him, which rises over time. She learns and evolves from each attack, so even when Korosensei sees through a firing pattern she adapts and lands hits, once blowing off one of his tentacle fingers.
Smog	Paralysing gas spray	An indoor anaesthetic gas Smog makes himself: a single breath can fell an elephant, and it breaks down on contact with outside air, leaving no trace. Grip sprayed it at Karma, but Karma had covered his mouth with a handkerchief and countered with an unused spray he had taken from the fallen Smog.
Grip	Bare-handed grip	The grip strength of a hitman who kills with his bare hands, strong enough to crack the glass of the hotel's view corridor with one hand. Knowing a single grab would finish him, Karma dodged every one.
Gastro	Marksmanship and sense of presence	Senses hidden students without seeing them. When Hayami fired first, he shot straight back through the narrow gap between the seats, narrowly missing her.

Season Summary

Season 1 — Season 1

Episodes 1–21

A creature that blew away 70 percent of the moon and vows to destroy Earth next March becomes homeroom teacher of Class 3-E, the looked-down-upon 'End Class' of Kunugigaoka Junior High, and the government offers a 10 billion yen bounty for the students to kill him by March. Karma back from suspension, the assassin English teacher Irina, the AI transfer student Ritsu and the tentacled Itona brought by Shiro all take their shots at him, while the students slowly regain their confidence. Nagisa beats the brutal PE teacher Takaoka in a real-knife match, and Class E wins its final-exam bet against Class A, earning a trip to an Okinawan resort island.

On the island, the class's all-out attack fails when Korosensei shrinks into an unbreakable crystal sphere, and soon half the class falls ill with an artificial virus. When an anonymous caller demands Korosensei in exchange for the only antidote, the healthy students and their teachers scale a cliff to sneak into his mountaintop hotel instead. Inside, Irina distracts the lobby guards, Karasuma knocks out the poisoner Smog before collapsing from his gas, Karma beats the bare-handed Grip, the girls slip through the bar with a cross-dressed Nagisa, and the boys seize two guards' revolvers.

In the concert hall, Korosensei directs the hidden class while Chiba and Hayami disarm the hitman Gastro. The mastermind on the top floor turns out to be Takaoka, seeking the bounty and revenge; on the helipad he makes Nagisa kneel and apologise, then blows up the antidote, and Nagisa, consumed by rage, picks up a knife and vows to kill him.

Music Releases

Jiriki Hongan Revolution (OP)
Hello, shooting-star (ED)