Episode Title:
Action Time.
Episode Description:
Koro-sensei is forced to watch an hour-long movie edited and narrated by Kōki Mimura exposing all of Koro-sensei's embarrassing habits, used as a distraction from the chapel slowly filling with water and bloating up his tentacles. Once the students of Class 3-E shoot off the seven tentacles, they surround and block Koro-sensei with a hydraulic cage, allowing Chiba and Hayami to snipe him. However, Koro-sensei activates his ultimate defense, trapping himself in an indestructible crystal sphere, which will last for one day despite his limited movements. As the students lament their failed assassination attempt, many of them suddenly and severely fall ill. This is revealed to be the work of a mysterious third party who had spiked their drinks with a supposedly deadly virus, demanding that the remaining students and teachers bring him the immobilized Koro-sensei in exchange for the antidote. Deciding against the trade-off, Koro-sensei and Ritsu instead come up with a plan to infiltrate the high-security hotel and obtain the antidote.
