Ep. 21: Koro-sensei menggunakan nama panggilan untuk membingungkan Gastro sementara Takaoka mengungkapkan rencananya yang melibatkan Kayano dan antidot.

With Gastro having a keen sense for determining an opponent's location, Koro-sensei gives instructions to the students using varying nicknames in order to confuse Gastro, giving Chiba and Hayami the encouragement to rise above their failed assassination and get the drop on Gastro. As the students approach the top floor, Koro-sensei deduces the mastermind isn't an assassin, while Nagisa learns Terasaka has been hiding the fact that he too was infected with the virus. Arriving on the top floor, the group discover the mastermind to be none other than Takaoka, who had planned to use Kayano in a plot to kill Koro-sensei when he emerges from his crystallized form. Wanting revenge for the humiliation he faced before, Takaoka calls up Nagisa for a rematch to their earlier knife fight. Despite Nagisa following Takaoka's demand to get on his knees and declare he's a coward, Takaoka blows up the antidote in front of the class, making Nagisa, who thinks everyone will die, pick up a knife in preparation to kill him. (Source: Wikipedia)
Episode
- Ep. 17 · Hinano dan Taiga bersiap sementara Lovro melatih para siswa untuk misi pembunuhan di pulau tersebut.
- Ep. 18 · Para siswa menghadapi ancaman virus sementara Koro-sensei tetap terperangkap dalam bola kristal yang tak hancur.
- Ep. 19 · Karasuma dan Irina menyusup ke hotel berjaga sambil menghadapi Smog dan Grip
- Ep. 20 · Karma Menghindari Serangan Gas Sambil Nagisa Menyamar sebagai Gadis untuk Membuka Jalur ke Lantai VIP
- Ep. 21 · Koro-sensei menggunakan nama panggilan untuk membingungkan Gastro sementara Takaoka mengungkapkan rencananya yang melibatkan Kayano dan antidot.
- Ep. 22 · Terasaka ikut campur saat Nagisa mengalahkan Takaoka dengan menggunakan teknik Lovro dan pistol kejut.