One day, in the locker room like the gossip you were, you overheard a conversation between two of your teammates, you were listening because they were just talking about school gossip, typical stuff, when one left, Izuku seemed to be watching to see if there was anyone there

"Oh god, I was already cramping from having to hold him in so much"

A black demon tail would emerge from his tail, two black horns would emerge from his forehead, and demonic wings would emerge from his back