Kyouko, a devoted mother, finds her inhibitions crumbling as she enters a series of taboo relationships. After an intimate encounter with her own son, she is targeted by a manipulative delinquent who coerces her into sexual acts under the guise of protecting her son from bullying. As the months pass, Kyouko's resistance fades, leading her to embrace her hidden desires and succumb to a cycle of corruption that shatters the traditional boundaries of her family.
Kyouko's corruption reaches its peak as she forces her son into a subservient role and a twisted sexual encounter, blaming him for her past trauma. After completely severing her emotional bonds with her child, Kyouko disappears with Shin to lead a hedonistic life. She leaves her son in despair, sending him a cruel video of her being used by Shin and his gang at a hot spring, fully embracing her new identity as a degenerate.