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 and Nagisa watch with their breaths held as Haruka and Rin engage in an intense race. However, they notice that Rin appears to be have changed. At the same time, Nagisa prepares to start up a swim club with help from Rin's sister Gou.

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.

There's trouble at the beach. The four swim club members are forced to revisit their motivation to swim. After Rei asks Makoto about his odd behavior during the training camp, Makoto tells them about his past.

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.

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

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!

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 to ensure the boys are getting the right nutrition to support their training. However...

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. But will every member be able to pass the prelims of his individual events?

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…

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..

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...

After the breakup of his middle school swim team, Ikuya decided to get stronger on his own and not rely on anyone. But Haruka, breaking out of his freestyle comfort zone to swim in the individual medley, tells Ikuya that he's not alone.