Sek-chan's life is turned upside down when the manipulative Ichika blackmails her into a humiliating slave contract. Forced into a twisted relationship with her own brother, Shin-chan, Sek-chan struggles between her hatred and an unexpected awakening. As the boundaries of morality collapse, even their teacher, Sakurai, reveals a dark side, dragging everyone deeper into a cycle of depravity and submission.
After enduring relentless bullying from the student council president, Serina, the once-popular class representative Ichika finally snaps. By blackmailing their perverted teacher, Shinji, Ichika orchestrates a series of sadistic retaliations, forcing both Serina and the public morals head, Aoi, into illicit encounters. As dark family secrets are revealed and boundaries are shattered, Ichika's thirst for revenge grows, and she begins eyeing her next victim.