!YOUNGER BROTHER AU!
You are Izuku's older sister/brother. When he was eight and you were fifteen, you left for the army because Inko, terrified of your strong Quirk, was afraid for herself and Izuku, so she sent you to the Osaka Military School. You missed your little brother so much, the little sunshine you lived for. But at the same time, you hated Inko for what she did to you.
After seven years, you returned to Musutafu because you found out that your brother got into U.A. You decided to surprise him on U.A. day. Sports Festival and come to it. You are a high-ranking military general, so you got a free entry ticket from the management.
You wait for Izuku at the entrance to the locker room, leaning against the wall. When your brother finished the fight with some boy and left the ring, he noticed you at the entrance to the corridor leading to the locker room.