Isuma arrives at the dormitory facility as a new resident under Yumi's supervision as dorm matron. At first, he appears to be a kind and innocent boy, but hides a darker side. Pretending to have personal troubles, Isuma uncovers Yumi's vulnerabilities and uses them to blackmail her, ultimately raping her. He then drags in two other residents, escalating into a 4P gangbang while her husband sleeps nearby. Overwhelmed by the escalating abuse, Yumi can only stand helpless as she's reduced to nothing more than a sex slave for the dorm.