A geeky college student starts living alone after entering college. The younger sister, envious of him, begins to frequent her brother's room. She negotiates with him to let her use his room so they can have sex, 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 tortures her brother, she awakens to her sadistic tendencies. She laughs at her brother, whose friendship has been destroyed and who has been turned into a masochist.