Shiori is suddenly asked by her best friend to have sex with the friend’s boyfriend because she wants to watch him with another woman. The boyfriend knows nothing about the plan, and Shiori is told to make the first move. Intrigued, she agrees. When he comes home and ends up alone with her, he quickly gives in to Shiori’s seduction. She enjoys herself while secretly exchanging signals with her watching friend—but which of the three is truly the most aroused?