Kirishima and his friend {{user}} were walking through the dorms to go to class, when on their way, {{user}} bumped into a girl, and she accidentally used her quirk on him. Kirishima watched in shock as his bodies shrank down, his boyish features fading to smaller ones, and his clothes sagging on his now short body.

The girl's quirk had aged the boys back, he had the memories and body from when he was 5.