Sex Exchange

Hikaru has been pining for his stepsister, Mioto. But she's going out with his friend Hakuro, and he ends up watching the two have sex through a peephole every day. Hikaru has also been sleeping with Akimi, and she walks in on him spying one day. Akimi is also Hikaru's stepsister. She formulates a plot to get Hikaru to love her and blackmails Hakuro into helping her, but things take a strange turn in a hotel room when Hakuro finds out this was all a plan to get him to reveal his real feelings to his stepsister Mioto.