Despite the fact that the Iwatobi High School Swim Club has been in existence for a year, new members have yet to join. Haruka Nanase and Makoto Tachibana, together with their younger companions Nagisa Hazuki and Rei Ryuugazaki, must find a method to recruit new members now that they are seniors. If not, the club will be compelled to close due to a lack of membership the next year. Meanwhile, with graduation fast approaching, it is time for seniors to consider their future plans. Unlike their buddy Rin Matsuoka, the new captain of Samezuka Academy Swim Club who is eager to pursue his ambition of becoming a professional swimmer, Haruka and Makoto are unclear about their future careers.