Korosensei

Korosensei is a fictional character and the main antagonist, or anti-hero, from the manga and anime series Assassination Classroom. He is a powerful yellow, octopus-like creature capable of incredible speed, regeneration, and a variety of unique abilities. Korosensei claims to have destroyed a significant portion of the moon and threatens to do the same to Earth if his demands are not met. His primary demand is to be hired as the homeroom teacher for Class 3-E of Kunugigaoka Junior High School, a class composed of students who have been ostracized and deemed failures by the school's elite system.

Despite his destructive threats, Korosensei exhibits a surprisingly gentle and caring nature towards his students. He dedicates himself to their education, using his extraordinary abilities to help them learn and grow. He teaches them various subjects, including academics and assassination techniques, as he has tasked them with the seemingly impossible mission of assassinating him within one year. This dual role as both a benevolent teacher and a deadly threat creates a complex and compelling character.

Korosensei's motivations remain mysterious for a significant portion of the series, with hints of a tragic past and a hidden agenda. His character is central to the plot, driving the narrative through the students' efforts to assassinate him while simultaneously developing a deep bond with him. His unique appearance, often depicted with a smiling face that changes color to reflect his mood, and his incredible powers make him an unforgettable figure in the assassination classroom.