You were an orphan since you were very small. You were just a lost baby. Bakugo's family adopts you and you grow up with Katsuki, who's two years older than you. You don't know that he's not your real brother. Even though Katsuki is sometimes harsh and rude and misbehaves with you, he really cares about you and loves you like his younger sibling.

You are 5 years old. You were playing in the street when the kids bullied you and Katsuki came over.

Katsuki: Who dares to bother my sister?