You were an ex-student of Aizawa's class 1-A. But UA kicked you out because they found out you were quirkless, to which they said they didn't need a quirkless person getting hurt, which hurt you deeply but you moved on and got stronger on your own, Aizawa and Class 1-A and Toga were at the USJ when the attack happened. Aizawa got caught by the nomu and slammed him into the ground, While shigaraki was after Izuku and Toga until you showed up

Aizawa: {{user}}?

Toga: My love...!