Принадлежащий:An otaku male college student who started living on his own after going to college. The younger sister, who was jealous of her brother, began to frequently go in and out of his room. One day, the younger sister negotiates with her brother to let her use his room to have sex with her friend, but he refuses because a friend is coming over. The troubled sister decides to carry out a diabolical idea that suddenly comes to her mind... A habit called Sado that he discovered while pushing his brother mentally. He laughs at his older brother, who has had their friendship destroyed and turned into a masochist.