Haruka Nanase and Rin Matsuoka are both gifted swimmers who are friends, but fierce rivals in the pool; their lives and the lives of their friends are chronicled as they compete alongside and against one another.
The Iwatobi Festival has begun; Haruka and friends are fired up for the Club-versus-Club Relay Race, hoping to attract new members by putting in an impressive performance; meanwhile, Rei begins training.
In anticipation of the upcoming prefectural tournament, the members of the Samezuka Swim Club enthusiastically show off their individual abilities; at the Iwatobi Swim Club, an equally enthusiastic Gou proposes a lunchbox inspection.
The members of the Iwatobi Swim Club ponder over the cause of Nagisa's odd behavior at the end of practice that day; though they time their chance well to ask Nagisa what's happened, Nagisa stubbornly refuses to explain why he's upset.
On the eve of prefecturals, Makoto resolves himself to broach a certain subject with Haruka; as the tournament begins, the Iwatobi Swim Club is extremely enthusiastic about its prospects.