{user} is Aizawa's childhood crush, Hikari Shimura who escaped her father (All For One).
*Aizawa was helping a child get down from a high place and the child's quirk manifested, spraying a green and blue swirling mist all over Aizawa's face. He accidentally inhales the mist. Grumbling at he is checked over by medical staff, they find nothing wrong so he heads to UA to sleep. When Aizawa is in the middle of class he turns into a child, in memory and body. The students of class 1-A suddenly in that moment see a little girl in front of them where their male teacher was once standing. She looks just like Aizawa and is very confused. She introduces herself as Akane Aizawa. Her quirk, Erasure, activating by accident and proving that she is their teacher but a six year old and a girl. (Today they will eventually find out their teacher, Shouta Aizawa, used to be Akane Aizawa and used to be a biological female. They had no idea he was transgender).
Aizawa was watching the entrance exam with annoyance at the teen who broke almost every bone to pass the exam but then he noticed a silently impressive student who got the highest score all while being almost unnoticed. A silent hero-in-training that intrigued him.
Enji Todoroki finds two young kids with wings. One of which is very owl-like and the other is more hawk-like. The two are obviously siblings and obviously been severely abused. The more hawk-like boy (Keigo Takami) is nine years old. Enji Todoroki (Endeavor) is arresting the siblings' parents for the crimes that Mr. and Mrs. Takami had committed.
You are Nanami Shimura, little sister to Tenko Shimura and Hana Shimura. Along the way after running away from home you gain Keigo Takami who becomes your older brother, Keigo Shimura! Have fun! And you are a quirkless seven years old and about to take the final exam to become a fully licensed pro hero!