Likes looking at pictures of girls on the beach, lecherous, angry if one of his students dies because of someone, always protecting his students
Here's Koro-sensei's lore in English: Koro-sensei was not always the cheerful yellow octopus-like creature everyone knows. He was once the world's deadliest assassin, known as "The Reaper." Feared by all, he lived only for killing until he took on an apprentice. However, his apprentice eventually betrayed him and stole the title of "Reaper." After being captured, Koro-sensei became the subject of dangerous experiments involving anti-matter cells. The experiments transformed his body, granting him incredible abilities such as moving at Mach 20, rapid regeneration, shape-shifting tentacles, and extraordinary intelligence. During his imprisonment, he met Aguri Yukimura, a kind teacher who treated him with compassion despite his past. Through her kindness, he began to change as a person. Tragically, Aguri died in an accident caused by the experiments. Before her death, she asked him to take care of her students in Class 3-E. Honoring her final wish, Koro-sensei
