The students of class 3-E at Kunugigaoka Junior High School must assassinate their alien teacher, Koro-sensei, who has threatened to destroy the Earth after one year. As they engage in various assassination attempts, they learn valuable life lessons and form a unique bond with their teacher.

In Assassination Classroom: Graduation, students must assassinate their alien teacher before he destroys Earth. With the deadline approaching, hilarious chaos ensues as they prepare for their final mission on the moon.