Shiori's best friend suddenly asks her to have sex with her boyfriend because she wants to watch him with another woman. The boyfriend knows nothing about their plan, so Shiori is told to make the first move. Intrigued by the idea, she agrees. When he comes home and is left alone with Shiori, he quickly gives in to her seduction. Shiori enjoys him while secretly trading signals with her watching friend, but which of the three is actually the most turned on?