Haruka Nanase has always been drawn to water and loves swimming. During elementary school, he and his three friends Rin Matsuoka, Nagisa Hazuki, and Makoto Tachibana entered a relay race together and emerged victorious. After the win, the quartet went their separate ways. Years later, as high‑schoolers they meet again; but Rin shows no interest in recapturing old times. He attends a different school, and his only goal is to prove he can swim better than Haruka.
Following the uneasy reunion, Haruka, Nagisa and Makoto decide to establish the Iwatobi High School Swim Club. They need a fourth swimmer if they are to compete in the upcoming tournament. Nagisa recruits Rei Ryuugazaki, a former track team member, to fill the spot. As the competition approaches, the four bond through rigorous training, aiming to finish first and finally resolve the rivalry between Haruka and Rin.
Kyoto Animation 
Animation Do Japan