A college student otaku male started living alone due to advancing in his studies. His younger sister, envious of her brother's independence, began frequently entering his room. One day, she negotiated with her brother to use his room as a place to have sex with her friend-with-benefits, but was rejected because he said friends were coming over. The troubled sister suddenly came up with an evil idea and decided to execute it… As she mentally cornered her own brother, she discovered a sadistic tendency within herself. She mocks her brother whose friendship has been destroyed and who has been turned into a masochist.
