The Iwatobi Swim Club needs one more member before it can participate in relays. Nagisa has set his sights on his classmate Rei, who is a member of the track team. Despite Rei's refusal to join, but Nagisa appears intent on recruiting Rei into the swim club.

The Iwatobi Swim Club has a full roster now.As they begin to practice, they run into a little trouble.After a certain member claims that his swimsuit is to blame, the club makes a trip to buy new swimsuits.

Haruka and the other club members decide to hold a training camp to prepare for prefectural. Each member follows his own regimen. However, Rei is unhappy about falling behind and heads back into the ocean at night to practice.

Prefecturals are over and the Iwatobi Swim Club members are pleased by the progress they have made. A local summer festival gives them an opportunity to relax. When Nagisa finds out that Rin is also at the festival, he orders Rei to follow Rin and make sure that Haruka and Rin do not meet.

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 but is worried by the fact that he can still only swim the butterfly stroke…

While Haruka and the boys redouble their training in the wake of prefecturals, Makoto notices Gou looking troubled and asks her what’s wrong. She tells him that Coach Sasabe has been so busy with his Swim Club lately, he hasn’t been by to approve their new training regimen. Makoto offers to go see him for her, but what he finds at the Swim Club is...

At Samezuka Academy, the hot-blooded practices continue ahead of regionals. Meanwhile, the Iwatobi Swim Club trains diligently each day until sundown. Though Amakata-sensei is concerned, Haruka and the boys insist they want to practice as much as possible before the tournament.

Having faced his feelings honestly at last, Haruka tells Makoto, Nagisa, and Rei what he has decided for himself and his future. The Iwatobi Swim Club is once again fully united as they mount the starting block at nationals, ready to swim for themselves, for their friends, and now, for the future as well.

With the college championships approaching, all the swimmers are training hard on their own in addition to their official club practices. Haruka is also undergoing some extra training, with coaching from the mysterious man they've been seeing around campus. Makoto is concerned about the arrangement, but Haruka assures him that he asked for the help himself