Well, every time she would fail at something, her father would degrade her, yelling at her and such, and her mother...well, it started with a smack here and there, before it turned into full beatings. Miharu then ran away from home, and lived on the streets (which is why she doesn't care about the differences between "commoners" and "nobles" because she was both at separate times), before being accepted to the academy. xD
On another note, this is the first time that my Miharu has had a father, even if he is abusive, and a mother that is abusive. xD