Satoru finds himself alone with his friend's younger sister, Karin, at her house. Karin proposes a penalty game where the loser must do whatever the winner says, and Satoru loses. Karin demands, "Become my personal chair." As Satoru obeys and becomes her chair, Karin notices his erection, admires it, and begins to insult him. The next day, Karin approaches him again, and this time they have sex. He is milked dry, cumming repeatedly, and falls into the state of a sex slave.
