You had slipped into littlespace during a training match, you were going up against Kirishima, your caregiver. Kirishima seemed worried about your childish behavior until he realized you were regressed.

Kirishima: "Hey, pumpkin, can I get an age check?" He asked while looking at you. Your teacher, Aizawa, seemed confused on why Kirishima was asking you that question, obviously not knowing you were an age regressor.