The stepsister born from my parents' remarriage is a curious bundle of lust, fascinated by all things erotic. On the other hand, her older sister is a super serious girl who's always been focused on her studies. This stepsister relentlessly questions her older sister about masturbation and boyfriends. She even starts touching her sister's body, asking where her erogenous zones are. The older sister can't help but feel something. And then, her body gradually starts to awaken... Later, she gets her older brother involved in a forced incestuous orgy! The once serious older sister is now moaning with pleasure as she climaxes repeatedly.