This adorable little sister's heat is irresistible! UMSO-496

A free-spirited sister, who harbors feelings for her socially awkward brother, one day devises a plan to trap him in his room at night. However, the brother successfully resists his sister's temptation and avoids danger. Dissatisfied, the sister invites her casual sex partner over to demonstrate their sexual encounters to her brother and prove herself. That night, the sister again barges into the brothers' room...