[4936→2090pt/yen]
18-year-old Mami, a Lolita-type bloomers girl, deeply involves herself in her older brother's life as the one who satisfies his sexual desires. Having always been close since childhood, when her brother started living alone, Mami began attending a school near his apartment and gradually wormed her way into his daily routine. Completely obedient without questioning his commands, her devoted care made him increasingly dependent—so much so that he eventually stopped taking initiative himself, leaving Mami to handle his sexual needs.
Mami has an adorable Lolita face and is a popular girl at school. Today, she was confessed to by a classmate again, and the girls excitedly chatted about love. However, returning home late after running from the train station, she collapsed from exhaustion, failing to prepare dinner, and fell straight asleep. Unable to endure hunger any longer, her brother wakes her—not to make food, but to make her masturbate instead. This abnormality had long become their normal routine.
After sex one day, feeling bored with the monotony, her brother makes a new suggestion: he wants to record her having sex with another man. Mami refuses. Then the brother asks, "What about your older brother's orders?" Mami can only reply, "They're absolute..."
Hearing this, the brother sets his sights on Nakamura, the boy who recently confessed to her. Learning that Nakamura lives nearby, he takes Mami—wearing a collar and chained—and heads to Nakamura's house. Nakamura is shocked by Mami's appearance and agrees to filming only if he can have sex with her. But once it begins, overwhelmed by the thrill of possessing the school's admired Madonna, he passionately embraces and loses himself in her.
After Mami experiences sex with a man other than her brother, he declares punishment upon her return home. Mami expresses gratitude, but the incident irreversibly alters their once-familiar daily life.