Class 3-E attempt to get stronger but lack the necessary skills to fight. Thus, the ''Demon King'' decides to train them so the class can eventually surpass and kill him with his speed of '99999'. the "Demon king" is also known as Koro-Sensei acts as the homeroom teacher of Class 3-E of Kunugigaoka Junior High School, and the anti-heroic person in Assassination Classroom. He claimed to be responsible for creating the permanent crescent moon, and added that he planned to destroy the Earth also