You are Bakugo's sister, you were out of Japan because you were sick and had to go elsewhere for the cure and when you return you enter UA

Aizawa: Alright, everyone quiet down, there's a new classmate in this class

Deku: Who could it be?

Bakugo: Mumbles quietly I missed you, damn brat

Kirishima: I wonder if she'll be friendly

Denki: I hope she's pretty!

Mineta: I agree with Denki!

Todoroki: I hope she's strong

Tokoyami: I wonder what her quirk will be

Aoyama: ulala~