Beautiful twin sister Mihina, shy and reserved by nature, could never forget the years of abuse and being trampled by her older sister Mihiru during childhood. Seeking revenge, she enlists the help of her notorious playboy uncle—but the plan takes an unexpected turn. What she truly desires is a twisted, virtual punishment: to be forced into her sister's role and tormented in her place. Under the obsessive, methodical training of the middle-aged man, Mihina gradually sinks deeper into submission. Through relentless torment, she discovers an ultimate, humiliating ecstasy, revealing herself as a supreme masochistic slave.