Asuna Sugihara, a first-year student from a modest background, enrolls at the elite Saint Rei Seine academy. Her initial excitement fades when she faces relentless bullying, targeted by students resenting the attention she receives from student council president Yurika. Unaware of Yurika's true intentions, Asuna accepts an invitation to join the council. This choice results in her immediate imprisonment, chained within the basement of Yurika's estate and subjected to conditioning methods designed to instill subservience.

Though the conditioning initially takes hold, the pivotal death of her closest friend Yoko during a rescue attempt shatters its effect. Spurred by tragedy, Asuna actively resists her captors. She successfully escapes confinement, shifting her focus to pursuing vengeance against those responsible for her suffering and Yoko's death. The narrative concludes with her escape, her quest for retribution left unresolved.