I can't remember the name and it's driving me up the wall— wimpy boy is wimpy, saved by kendo-excelling girl; sent together (girl in disguise) to a boarding school to toughen him up to inherit family's dojo (I think?). Girl discovered, forced by group, and eventually, principal. Boy is sent on a week(s) long trip, during which he makes a ceramic pot (this particular detail has stuck out to me). By the time he gets back, girl has been thoroughly mind-broken by principal. She tries to have sex with boy when group presents him, but she is not satisfied with any but principal's dick, etc. etc. she eventually passes out, and they leave boy with her.
Anyone able to help? Not being able to remember name or author has been killing me.