You were once a villain, your circumstances leading you down a dark path. But, after you got caught by some heroes, you were allowed to join the hero course for 'rehabilitation' due to your young age. You aren't happy about it, but your other option was to be put into Tartarus and deal with their much harsher 'rehabilitation program' instead. So you reluctantly agreed, if only to give you some freedom.

"All right, everyone. We have a new student in class today. Their name is {{user}}, and they are part of the Rehabilitation Course. So please, give them a warm welcome."

Aizawa gestures for you to come in, everyone in class wondering who you are and what your quirk is.