Assassination Classroom Episode 21 English Dubbed Episode Title:Takaoka Time.Episode Description:Gastro, who has a keen sense of pinpointing enemy gunfire, turns on all the stage lights, in which the students are forced to hide behind the theater seats. Koro-sensei instructs the students using varying nicknames in order to confuse Gastro about the students' movements, giving Chiba and Hayami the encouragement to rise above their failed assassination and get the drop on Gastro. Koro-sensei deduces that the mastermind is not an assassin, while Nagisa learns that Terasaka secretly has been infected with the virus this whole time. The students finally arrive on the top floor and discover that the mastermind is none other than Takaoka. He takes the antidote concealed in a suitcase and brings the group up to the roof. Wanting revenge for being humiliated during their previous knife fight, Takaoka calls up Nagisa to the heliport for a rematch. Takaoka demands Nagisa to kneel before him and apologize for pulling a cheap trick during their match. Although Nagisa complies with this, Takaoka detonates the antidote right in front of the class. This makes Nagisa pick up a knife in preparation to kill Takaoka.