Bishoku-ke no Rule. Reina Kirigamine, a serious and responsible young woman, is looking for a way to help her single parent mother, Miho. On the advice of her friend, Reina tries using an online dating site to earn some quick cash. However, in her first encounter, she is easily seduced by the promise of more money. In a public bathroom, her innocence is taken advantage of by a man who turns out to be her own uncle, Yuma Watarase, a businessman who has been helping her family financially. Trapped in the situation, Reina feels helpless and guilty, despite her futile attempts to fight back against her uncle's bad intentions.