Episode 21

Takaoka's Time (initially titled XX Time) is the twenty-first episode of the Assassination Classroom anime. The episode first aired on June 12, 2015.

Summary
As the group of Class E students continue to the top floor, they run into Gastro and must fight him. If they survive this, will they finally see the identity of the person behind all this!?

Plot
The class's way forward is blocked by Gastro at the theatre room, who despite not seeing anyone senses their hidden presence. Gastro demands the group to come out of hiding when Hayami suddenly fires a shot that misses his gun. Gastro fires back, shooting through the small gap between the seats and narrowly missing Hayami. The hit man tells the class that the theatre is soundproof so that no one outside can hear the shots. After telling Hayami to stay put and Chiba to hold fire, Korosensei is stealthily taken to the front row and distracts Gastro. Gastro marks Hayami's position but Korosensei starts barking out orders for the class to move around and subtly move forward. He initially calls the students by their name but soon calls out code names that only the class will understand, thereby confusing Gastro.

Despite his confusion, Gastro deduces where he thinks Chiba is hidden, having not moved at all and hearing heavy breathing coming from the same spot. Korosensei then tells Chiba to fire. His silhouette pops up from behind the seat and Gastro fires at it. However the silhouette is revealed to be a decoy made by Sugaya, as the real Chiba pops up elsewhere and fires a shot. Gastro mocks his aim until a theatre equipment drops on top of him. While still disorientated, Hayami fires a second shot, this time shooting Gastro's revolver off his hand successfully. The boys immediately pin the hit man down and tie him up. The class congratulate themselves while Karasuma states that they are still high school kids despite having just faced a life-and-death shootout.

Finally at the top floor, Karasuma is now mostly recovered and chokes a lone guard unconscious. Before heading off, Nagisa notices Terasaka to be somewhat uncomfortable than usual. Nagisa feels a fever and realises that Terasaka had also been expose to the illness but the latter forcefully silences him. They silently make their way to the mastermind's room and see a briefcase strapped with explosives. The class prepare to jump on the man and disarm him of the remote detonator on the table when suddenly the man speaks and throws a bunch of other remote detonators in the air. Not knowing which is the real one the class hesitates, and discovers in horror that the mastermind behind the friends' illness is none other than Akira Takaoka, with scars on his face and an insane look in his eyes. When Karasuma asks why he is doing this, Takaoka simply claims that he wants the bounty and exact vengeance on the class for humiliating him since returning to the Ministry of Defense. He singles out Nagisa in particular, believing that he only won their last fight by using dirty tactics. Terasaka retorts that Nagisa won according to the rules set by Takaoka himself but the crazed former soldier swiftly drowns him out.

Takaoka has the class follow him to the helipad on the rooftop and beckons Nagisa to fight him once more if he wants the antidote. Despite Kayano's plea of how dangerous the situation is already, Nagisa obeys and steps onto the helipad. Takaoka then destroys the stairs to prevent anyone else from interfering. Nagisa attempts to negotiate for the antidote but Takaoka instead makes Nagisa bow down to his knees and apologise for that day. Nagisa relents despite knowing how humiliating it would be. The soldier then remarks that it still does not satisfy him and wishes to see the despair on Nagisa's face, and suddenly blows up the briefcase containing the antidote vials. The entire group watch helplessly as the only way to save their friends has been destroyed in an instant, and Nagisa looks despairingly at Terasaka, who is struggling to remain standing. Overcome by bloodlust, rage and despair, Nagisa picks up the knife dropped by Takaoka and says that he will kill him.

Episode Notes

 * The episode was originally titled "XX Time." This mirrors the manga where the title of chapter with the same name was crossed out.