A girl

So in this story, Chihiro will have his gender-reversed so he was always a she.

Now then, what could possibly happen to such a shy and cute girl that would leave her exposed?

Does one of his classmates think she's a guy and tries to prove it? Does one of her classmates sabotage her in a humiliating way? Or does someone try to get her to act more like her gender in an embarrassing way?