Haruka Nanase/Story

Season 1
Second year high school student, Haruka Nanase, has a fascination and love for water. He struggles to move forward in life while remembering his elementary school days as a competitive swimmer. In the present, Makoto Tachibana, Haruka's best friend, picks him up daily for school at Iwatobi High. While having lunch, they encounter a former teammate and friend, Nagisa Hazuki. Nagisa suggests they visit their old swim club in order to dig up a time capsule containing a relay trophy they won with their other teammate and friend, Rin Matsuoka.

That evening, while there, Haruka reminisces over a photo of the race and the group is surprised to run into a completely changed Rin in the hallways. Rin is rude, immediately challenging Haruka to race until they discover that the pool is empty. The next evening, Makoto, Nagisa and Gou Matsuoka, Rin's younger sister, visit Haruka. Makoto and Nagisa convince a reluctant Haruka to visit Samezuka Academy, where Rin attends school, by tempting him with swimming in their indoor pool. Upon arriving, they wait until the swim team is done with practice and break into the natotorium where they are discovered by Rin who orders them out. Haruka then steps out of the pool and challenges Rin to a freestyle match.

While continuing the restoration of Iwatobi's outdoor pool, Gou, still confused by her brother's behavior, asks Makoto about their race and learns that Haruka threw the match, allowing Rin to win since he was merely content with being in the water. When Rin finds out, he's furious. Later that evening, Makoto runs into their old coach, Goro Sasabe. Sasabe reveals that Haruka and Rin had a race when the latter makes a rare return to Japan during middle school, which Haruka easily wins. Rin, seemingly distraught, says he's quitting swimming which creates a rift between the swimmers and causes Haruka to also quit competitive swimming.

When Haruka, Makoto, Nagisa and Gou finally restore the Iwatobi pool, Haruka jumps in despite the cold weather and catches a cold. Meanwhile, the newly formed team is tasked with finding a fourth member which turns out to be Rei Ryugazaki due to Nagisa's persistent efforts. The only problem is that Rei doesn't know how to swim.

The group goes shopping for new swimsuits where Haruka and Rin run into each other and have a discussion about their differing forms and Rin demanding a race with them both in peak condition, saying he won't be able to move forward otherwise. They agree to settle the score at the upcoming tournament.

Before the tournament, the Iwatobi team each try to teach Rei how to swim, unsuccessfully. Even Haruka, who admits that he, too, isn't compatible with other techniques in that he doesn't swim freestyle by choice, but simply because it's all he can swim. Hearing this, Rei attempts the butterfly stroke and finds himself able to swim with that technique.

Gou proposes they use a decades old training regiment and venture to an island for a summer training camp. Haruka expresses concern for Makoto who had a scarring experience with the ocean in the past, but which Makoto dismisses. This leads to one of Makoto's backstories, as he has always been afraid of the ocean.