A geeky college student starts living alone after entering college. His younger sister, jealous of her brother, begins frequenting his room. One day, she tries to negotiate with her brother to borrow his room to have sex with her sex friend, but he refuses, saying that his friends will be coming over. In a pinch, the younger sister suddenly comes up with a diabolical idea and decides to put it into action... As she drives her brother to the brink, she awakens her sadistic tendencies. She laughs at her brother, whose friendship has been destroyed and who has become a masochist.