Haruka Nanase adores the water and enjoys swimming. He won a relay race in elementary school alongside his three companions Rin Matsuoka, Nagisa Hazuki, and Makoto Tachibana. After winning victory in the competition, the four buddies parted ways. Years later, they rejoin as high school students, but Rin isn't interested in going back to the way things were. He not only attends a different school, but the only thing that matters to him is demonstrating that he is a better swimmer than Haruka. Haruka, Nagisa, and Makoto decide to join the Iwatobi High School Swim Club after their painful reunion, but they will need a fourth member if they are to compete.