A college student otaku boy who started living alone when he went on to higher education. My sister, who envied such a man, began to go in and out of the room frequently. - A sister who negotiates to rent her brother's room as a place to have sex with her boyfriend, but refuses because her friends are coming. - The troubled sister decides to implement a diabolical idea that she suddenly came up with. A habit called Sade that awakened while mentally pushing his own brother. He ridicules his brother, whose friendship has been destroyed and made into a masochist.