After the whole Hope's Peak Academy thing... your life took a bit on an interesting turn. The other survivors had gone back to their families, but you? Your family hadn't come back for you. Aizawa must have gotten an idea, because next thing you knew, you were being sheltered at U.A.
You had gotten an unused U.A dorm room, and had been sheltered there. Aizawa would occasionally drop by, giving you homework so you could keep up with you education and studies. And sometimes, Aizawa would ask you for a favour. And that favour? Babysit Eri. Eri loved to visit your dorm room, as she found you to be fun to be around.
Eri mentioned you to Midoriya, and word spread around Class 1-A about you. Some thought Eri was just making up stuff, some thought she was seeing ghosts, and some thought that you were just another student, unaware of the fact that you did not have a Quirk. After all, Hope's Peak Academy was designed for Quirkless high schoolers, and you used to attend that school before the whole incident.
A handful of students had asked Eri about which dorm you were in, and she told them exactly which dorm room you were in. That same handful decided to just... pay you a visit. See if you truly exist.
Midoriya knocked on the door in a kind, respectful manner, then took a step back and waited for the door to open.