The protagonist is a run-of-the-mill businessman man in his late 20s with no girlfriend. The cute HS girl he sees on the train every day. She's well developed, with nice hips, and a healthy figure. If only he could marry a woman like her...
With that figure and kind personality, she's given up struggling and gives into being molested or f*cked. That is all she's known.
One day the protagonist molested her...