The story revolves around a 13-year-old boy named Tomo who develops a taboo attraction towards his new step-sister, Mio. She's 20 years old and seems to reciprocate his feelings. One day, they get intimate in her room with him undressing her slowly as she guides him along. They engage in their first sexual encounter, which is passionate and full of moans from both of them. Their relationship continues with them engaging in various sexual activities, including oral sex and anal play. As days pass, their desires grow stronger, leading them to become addicted to each other. Despite knowing it's wrong, neither of them can resist their intense urges anymore.
