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.

Haruka and his friends have grown after last summer's tournament; amid the hustle and bustle of training for their individual events, their daily lives continue as usual.
The crew ponders how to attract new members to the Swim Club; Haruka is called in by Amakata-sensei to discuss his intended career path, but as always, Haruka moves to the beat of his own drum.
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.