The series begins when the protagonist is summoned by the busty school nurse, Momoka, who coerces him into various sexual acts in her infirmary. [2] The lewd education continues when he catches Momoka's younger sister, Maron, pleasuring herself. [2] Instead of being embarrassed, Maron turns the tables, stripping him down and using her hands and feet to bring him to climax before ultimately demanding he fuck her virgin pussy raw. [2] The entire sordid affair culminates in a steamy threesome at a public bathhouse, with both sisters eagerly servicing his cock and getting filled with his seed. [2]