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.

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.