Haruka Nanase is the centerpiece of the story, consumed with his passion for water and swimming. His elementary school days found him swimming competitively alongside his teammates, Makoto Tachibana, Nagisa Hazuki, and Rin Matsuoka; a victory before their separate paths took them in different directions. Now in high school, Rin re-emerges on the scene, challenging Haruka to a swim match where his superior skills are revealed. Haruka refuses to let things end there. Instead, he reconnects with Makoto and Nagisa, inviting newcomer, Rei Ryugazaki, to form the Iwatobi High School Swimming Club as a means to defeat Rin's prowess.