In a twisted intersection of abnormal desire and deep affection, a minor misunderstanding spirals into tragedy. As she spends time with an older coworker, her brother grows increasingly jealous and anxious. Eventually, he rapes her, completely altering the course of her life. From that night on, she is trained daily by her brother's hands—Mao, the younger sister, suffers at first, yet gradually begins to understand her inner self. Enduring his perverted fetishes, her masochistic nature slowly awakens, and she starts craving her brother's cock on her own. No longer just a victim, she transforms into a willing sex slave consumed by desire. And then, she confesses: "I... get raped by my brother every single day..."