Korosensei decided to teach the class to fulfill a promise to Aguri Yukimura (the former teacher of E-class), and made up the story that he destroyed the moon and the whole assassination thing, just so he would be allowed to teach. Korosensei and his apprentice Shinigami.
He didn’t actually blow up the moon. When he was captured, a scientist used him in his experiments, and to compare the results, the same modifications are done to a lab rat. They put the rat on the moon, but then it exploded 70% of it. So naturally they think that Korosensei also has the potential to do that to earth.
It’s Kataro who is actually the overarching antagonist of the series because he made Koro-Sense what he is and he was the one responsible for destroying 70% of the moon. Kataro loses his mind and just to kill Koro, he decides to become a tentacle monster himself.
Korosensei has the appearance of a yellow octopus. He is about three meters tall and possessed a large, bulbous head with a large smile that rarely breaks or moves and small, beady eyes. … As a human, he had pale skin, a slender build, dark eyes, and short black hair that reached to his nape.
The two often hang out together and seem to enjoy the same things like movies. Karma also enjoys teasing Nagisa and often has many creative methods to do so; many of which poke fun at his androgynous appearance. Despite that, Nagisa really doesn’t mind it and isn’t very offended by Karma’s teasing.
Nagisa is a petite-framed boy with blue hair and azure eyes. His hair goes past his shoulders due to his mother forcing him to keep it that way. He kept it in a long ponytail until Kaede Kayano joined the classroom and styled it in two pigtails.
Korosensei decided to let her attack his main weak point, so one of the students can distract Kayano from her bloodlust. Then, Nagisa kissed Kayano to calm her bloodlust, getting 15 hits on her. After that, Kayano started to drown in her romantic feelings for him.
Koro-sensei probably doesn’t have enough power to defeat Goku. Assuming Goku never learns that anti-Koro-sensei weapons are the only thing that can kill him, they’ll both fight each other until they reach a stalemate and get tired. Kuro doesn’t have any experience fighting anyone on his level.
He underwent a grotesque transformation because he felt that he was giving up his humanity and becoming a monster. Finally, his transformation to yellow occurred after he escaped in 140, underground. This lovable yellow form was because of his emotional change.
Aguri unfortunately died in an accident while Koro-sensei destroyed Yanagisawa’s research lab. In her final moments she asked Koro-sensei to teach Class 3-E in her place. As a result, he takes his job as a teacher very seriously.
Eventually Korosensei won the fight but physically exhausted. When Korosensei reaches the final moment of his life, Karasuma was entrusted by Korosensei to look after the Class E after they graduate. He says his name (Koro-sensei) for the first time before his execution by Nagisa.
Korosensei had the appearance of a yellow bipedal octopus. He was about three meters tall and possessed a large, bulbous head with a large smile and small, beady eyes. He used two feelers as arms, with two fingers each, and utilized the rest of his tentacles to walk with.
No. Koro-sensei is not evil. … After her death, Koro-sensei decided to spend the rest of his life taking care of Aguri’s students, which was exactly what she asked him to do. Also, Koro-sensei wasn’t the one who destroyed the moon, and he didn’t have any intentions on destroying the Earth.