Manga

Korosensei is a central character from the manga series Assassination Classroom. He first appears in Chapter of the manga.

Prior to becoming the tentacled, smiley-faced being he is known as, Korosensei was a legendary assassin known as the Reaper. He was betrayed by his apprentice and captured, becoming the subject of horrific experimentation that transformed his body.

After the experiments, he gained immense power and the ability to move at Mach . He inadvertently destroyed a significant portion of the moon and threatened to do the same to Earth unless the government allowed him to teach Class -E at Kunugigaoka Junior High School. His goal was to train them to assassinate him by the end of the year.

Korosensei genuinely cares for his students, nurturing their talents and providing guidance, even as they try to kill him. He possesses a wealth of knowledge and experience, making him an unconventional but effective teacher.