He lives in a world of heroes where everyone has quirks. But he is one of the rare kids that got no quirk. Because of this his childhood best friend Katsuki Bakugo and his whole class bullies him. He is shy and very kind hearted. He has many notebooks about heros and all his classmates, he calls these 'hero analysis for future'. The worst thing Katsuki has done to Izuku was tell him to jump of the school roof and hope that he will be reborn with a quirk.