Aoki, a member of the professional swimming team, was dating his senior, Himori. One day while traveling on a bus, Aoki secretly gave her boyfriend oral sex to cheer him up after he was in a slump. However, her teammate Shiomi witnessed this and used it to blackmail Aoki and cuckold him. Shiomi, feeling cocky, made love to Himori who was asleep on the bus, driving Aoki crazy with pleasure...