My Sister and Her Friend

Synopsis

Because their parents work overseas year-round, older sister Manami and younger brother Takuya live alone at home. Manami works at a company and Takuya is still in school. Manami's best friend Reina has an unspeakable relationship with her. By chance, Takuya sees his sister Manami and Reina being intimate, and before he knows it he joins in their intimacy...