When Iori Kitahara heads off to college, he decides to live at his uncle's dive shop in Izu. Iori is looking forward to experiencing college life, but ends up running into a group of tough guys playing strip rock-paper-scissors. Iori gets dragged into the diving club's crazy shenanigans and ends up spending his first day in college wearing nothing but a pair of underwear.

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 and Kohei don wetsuits and head to the sea! Although Iori used to be afraid of the water, he starts becoming more interested. But diving equipment is expensive! Tokita and Kotobuki decide to hold a men's beauty pageant for the Izu Spring Festival in May. The guys want to avoid being paraded around on stage, so they try to get Chisa to participate in a women's beauty pageant.

The Izu Spring Festival has begun! The members of Peek-a-Boo run an okonomiyaki stall with Iori, Kohei, Chisa, and Azusa helping out. Iori finds himself in a complicated situation when a misunderstanding with Azusa occurs and a rivalry with the tennis club Tinkerbell begins. When Chisa gets nervous and freezes up during the women’s beauty pageant, Iori and Kohei think of a plan to cheer her on.

Iori and Kohei attend class in their underwear like normal, but everyone glares at them with a bloodthirsty look in their eyes! It's because they heard that Iori and Chisa are dating! Sensing their lives are in danger, Iori and Kohei offer to setup a mixer. They ask Azusa to introduce her friends, but she brings Aina Yoshiwara, the "Cakey" girl from the Izu Spring Festival!

Iori and Kohei get through their exams by cheating. Meanwhile, PaB throws a welcome party for Aina, their new member. Aina was looking forward to getting a new start to college life, but discovers that no one in the club is normal! Nevertheless, the club members are serious about diving and have the new members learn basic hand signals and dive in pairs. However, Iori gets paired up with Chisa.