After a cutthroat battle with Kohei Imamura, a handsome otaku from school, Iori ends up joining the Peek-a-Boo diving club. Iori arrives home worn out from the day, but perks up when he hears about a party with a women's college. However, his cousin Nanaka won't allow him to stay out three nights in a row, so Iori tries to show her he's an independent man to get her to let him go.

Iori tries to setup another mixer for his friends, and wants to ask Chisa to introduce her friends so they can all play truth or dare. Nanaka and Azusa also get involved, and they all begin a vicious game of attack and defense! However, Iori doesn't have enough money for their trip. Iori and the gang head to a diving shop to buy diving gear, but find out there's still a lot they don't know.