Despite being in existence for a year, the Iwatobi High School Swim Club remains without any new recruits. As seniors, Haruka Nanase, Makoto Tachibana, Nagisa Hazuki and Rei Ryuugazaki must find a way to draw in new members, or risk their club closing due to a lack of membership in the upcoming year. While graduation quickly approaches, the seniors face the task of deciding their own future plans. Unlike Rin Matsuoka, their friend and the newly appointed captain of Samezuka Academy Swim Club, Haruka and Makoto feel uncertain about their career paths. Adding to their difficulties, the arrival of Sousuke Yamazaki, an old acquaintance of Rin's and a highly scouted swimmer, threatens to create tension between him, Rin, and Haruka. Sousuke's enrollment at Samezuka Academy could have consequences for their friendships as they each come to terms with their changing futures.