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.

As the tournament continues, Sousuke finally tells Rin about how he’s passed their years of separation. Rin is concerned at Sousuke’s nonchalant attitude toward certain things and tries to speak his mind. Meanwhile, the Iwatobi Swim Club looks toward the relay final.

Upon Rin’s invitation, Haruka finds himself venturing to “a certain country.” Knowing that Haruka has hit a wall worrying about his future, Rin opens up and speaks to him about his own thoughts and feelings. Afterward, Rin quietly asks Haruka what he will do about his own future...

The Iwatobi Swim Club must win to advance to nationals. As the tournament draws near, the members get nervous. Meanwhile, Rin grows increasingly irritated. As it comes time for the medley relay, each member must find their own answer as they step up to the start line

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.

The Iwatobi Swim Club continues their training. However, signs of confusion seem to keep surfacing in the silent Haruka’s swimming. Makoto and the others are worried about him, but try to continue acting cheerfully as though nothing was wrong. But one day, Sousuke appears, asking to speak to Haruka…

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…

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...

Haruka, Makoto, Nagisa, and Rei swim in their individual events. Rin becomes irritated as he remembers watching them swim back in grade school. Afterwards, the four Iwatobi Swim Club members must prepare for the medley relay.

Haruka and his friends have grown after last summer’s tournament. Amidst the hustle and bustle of training for their individual events, their daily lives continue as usual. However, a new season now approaches!

Rin, now living in Australia, trains hard every day with swimmers from all around the world. Then a Japanese guy shows up where his team is training, challenging each of his teammates to races and beating them one by one. Even Rin is surprised when this newcomer reveals his identity...

Haruka has entered Hidaka University, where he's now training with the swim club to prepare for a newcomer tournament. One day, he runs into Asahi, a swim teammate from middle school. Haruka is later joined by Makoto, who also moved to Tokyo, at a coffee shop to catch up with Asahi... and the topic quickly turns to Ikuya, another teammate they swam with in middle school. On the day of the newcomer tournament, Haruka and Asahi are in the same race for the first time in years... and the spectacle is watched by Hiyori, who calls Haruka an "inferior copy of Ikuya." After the race, as Haruka is walking through the halls with Asahi, he catches sight of Ikuya passing by..

Haruka and his relay teammates decide to hold a training camp in the summer of their second year of middle school. During the night, Haruka heads out to the pool and finds Ikuya looking up at the stars.

Haru, Makoto, and Asahi visit Shimogami University in hopes of talking to Ikuya, but even after looking all over campus, they can't find him. Hiyori, however, notices them and makes it his mission to keep them from seeing Ikuya.

The Iwatobi High School Swim Club is participating in a joint training camp with the Samezuka Academy and Soufuukan High School teams. Sousuke is also participating as an alumnus. In the midst of the excitement, Rei and Nagisa notice that something is odd about Romio's swimming. Then Shizuru tells them the story of what happened to Romio in middle school...

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

Hiyori still remembers the first time he saw Ikuya smile. Both boys grew stronger through rigorous training while they studied abroad in America... but seeing Haruka threw Ikuya off his stride. Now Hiyori wishes Ikuya would just forget about Haruka for good.

After hearing about what happened in the past, Rei goes to Samezuka Academy to ask Rin what he wants. The night before Iwatobi and Samezuka leave for regionals, Rin calls Rei to explain how he feels about the relay. And then, Samezuka announces its lineup for the relay.

Haruka's next race is the All-Japan Invitational, which determines who will represent Japan at the global level. To prepare for this important tournament, Haruka is invited to a special training camp.

After spending their first year of high school in peace and quiet, Haruka and Makoto run into Nagisa, a new student who was a member at a swimming club with them when they were kids. That swimming club is being torn down, so the three of them sneak in to dig up a time capsule that they buried in the back, which is when they are reunited with Rin, the fourth member of their group who left to study abroad.

Makoto has been unable to get in touch with Haruka following the friendly race at his training camp, making him worry that Haruka is dwelling on what happened. Then Nao approaches Makoto to tell him about a rumor he heard.