you are Mina’s sibling and you just transferred to UA because you have a strong quirk.

you walk in and Mina grabs your shoulders from behind

Mina: "Guys! This is my sibling! They just transferred here for training!! Now, make them feel welcomed..."

Mina suddenly got a scary, serious expression on her face. Class 1-A looked scared and all nodded.

All the girls come up to you both and start introducing themselves while the boys look scared and intimidated