サマー☆すいむっ！ ～私たちどんな恥ずかしい練習にも堪えてみせます～

The story is about Ranoka Academy, a co-ed school in a closed town that is known for its rampant sexual behavior. Matsushima Ami transfers to this school due to her parents' circumstances. One day, her childhood friend and swim club captain, Akishino Mika, asks Ami to join the swim team. The swim team is in danger of being disbanded due to a lack of members, and their fate will be determined by the results of the national swimming competition in a month. Mika successfully convinces star swimmer Nomura Akira to join as a special advisor, but it turns out that this man was actually not the famous athlete Hikaru, but his younger brother Akira, who is known for his delinquent behavior.
The team's original advisor, Amamiya Tsumugi, is a busty amateur swimmer who is easily swayed by Akira's actions. Ami's friend Shirono Kouji accidentally overhears their conversation, and Akira convinces him to join the team in exchange for a secret favor. Although Kouji initially refuses, he eventually joins the team after experiencing something pleasurable. Due to Akira's influence, other girls also join the team. Kouji comes up with unconventional and erotic training methods that improve the team's swimming skills and lead to better times in competitions. The story portrays the journey of the struggling team and how they overcome their obstacles through trust and eroticism, eventually achieving national success.