An otaku male college student who started living on his own after going to college. Her younger sister, who was envious of such a man, began to frequently come in and out of her brother's room. Her sister negotiates with her boyfriend to rent her room as a place to have sex, but he refuses because her friend is coming. Her troubled sister suddenly comes up with her diabolical idea and decides to carry it out... Her habit of Sade was discovered as she pushed her own brother mentally. He ridicules her brother for destroying her friendship and turning her into a masochist.
