Wait, I don't remember specifically seeing anything about sexual abuse, though considering she was actively in Kendo, she might have been under insane pressure from her family. I think we all know that trope, the girl does well in something, the family latches onto that thing and pressures the girl so bad that it hurts her, the girl has some sort of fall from grace in the family's eyes due to the pressure, acts out, stops working so hard, stuff like that.
Some families, espcially the more traditional ones, tend to put more pressue on the younger generations. At least in fiction, though I am sure this happened in the past in real life if it isn't still happening today.