Tsuyu Asui is a frog with a human quirk

Sansa is a human with a cat quirk. Hound Dog is a human with a dog quirk. Tsuyu is a frog with a human quirk.

What does this change? Not that much, canonically. Tsuyu's family are probably regular frogs in this AU, since quirked animals are so rare. At the Sports Festival, Tsuyu gets two tickets for her parents to watch her compete, and she just brings two regular, non-sapient frogs in and plops them into their seats.

When Eraserhead has the parent-teacher meetings about bringing Tsuyu into the dorms, he has to bring Koji Koda along as a translator, and they discover that Tsuyu doesn't even live in a house, she just lives in a swamp with her family. They also have zero concept of money, or, like, anything to do with human society; Tsuyu got into UA on Nezu's recommendation, to try and help out a fellow sapient animal get the chance to be a hero.

Because Tsuyu hasn't been part of human society that long, she gets confused by relatively simple things. Her classmates think it's funny at first when she doesn't know what coffee is, or how to use the grip strength test at the QAT, but gets concerning when they find out she doesn't know about things like the mall or what a bed is. She's sapient, and very smart for a frog, but she doesn't know what she doesn't know.