When Haruka, Makoto, Nagisa and Rin were in elementary school, they swam together in a relay race and won the match. As Rin was on his way to Australia to train to become an Olympic champion, the gang decided to bury their trophy in a time capsule and retrieve it when they all had grown up. Now, Haruka, Makoto and Nagisa have reunited in high school and decide to dig up the prize. But on the way there, they run into none other than Rin, and he's determined to show Haru who's the best! As a result of this fateful meeting, the three friends decide to start a swim club, along with fellow classmate Rei, and their rival's little sister Gou as the team manager. Can the gang hold their own against Rin and prove their skills at the Prefectural Tournament?