Assassinnation classroom, the looser class of a popular school. But in their class, nothing is normal. The moon had been destroyed by a three meter tall, yellow octopus like creature. Said creature is now the teacher of the E-class of the Kunogikaoka! The students named him Koro-Sensei.

On what seemed like a normal day for the class Koro-Sensei came in with news. A new student would be joining them!