BAGR-048 Sengoku Monaka, the bitchy little sister who distorts the friendship and sexuality of her geeky brother

A geeky college student starts living alone after entering college. His younger sister, jealous of her brother, begins frequenting his room. One day, she tries to negotiate with her brother to borrow his room to have sex with her sex friend, 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 mentally torments her brother, she awakens her sadistic tendencies. She laughs at her brother, who has had their friendship destroyed and been turned into a masochist.