Iwatobi High School Swim Club

The Iwatobi High School Swim Club is founded by swimmers Haruka Nanase, Makoto Tachibana, and Nagisa Hazuki with Gou Matsuoka as manager and Iwatobi High School classical literature teacher Miho Amakata as faculty advisor. Rei Ryugazaki later joins as the necessary fifth member to create a school club and four swimmers needed to participate in events and engage in joint practices with the Samezuka Academy swim team.

Iwatobi High School would not fund the swim club until it had accomplished something, which prompts the club to train for competitions. After winning a relay and qualifying for a regional competition, the club gains recognition and is encouraged to aim for nationals. At the regionals, however, the team is disqualified when an illegal substitution is made for the relay. The substituted member is Rin in place of Rei, who gives up his place to restore the friendships Rin had with his former elementary school teammates. Were they not disqualified, they would have won first place.

Despite an impressive club debut and amazing performances during the prefecturals and regionals, the swim club failed to gain new members, causing insecurity among the younger members who feared the club would be dissolved once Markoto and Haruka graduated. They are seen trying to gain new members by posing athletically in their swimsuits during the club introduction ceremony for the first-years and winning the club-versus-club relay race held during the Iwatobi High School cultural festival. All this to no avail. Nagisa even suggests to Rei that they parade naked around the school, which Rei declines asking "Where did the swimsuits go?!". After that, Nagisa suggests composing a song until Rei learns he will have to compose it and sing it solo. In the end credits, Rei and Nagisa are shown as third-years performing a recruitment skit during the first-year assembly. Later, four students join them at the pool.

In Free!-Take Your Marks- and Free!-Dive to the Future-, it's revealed that Rei Ryugazaki is the new captain and Nagisa the new vice-captain. New member Ayumu Kunikida is a new manager, along with Gou. The swim club also manages to recruit two first-year students, Shizuru Isurugi and Romio Hayahune.

The club's mascot is Iwatobi-chan (岩 (iwa) = rock, 鳶 (tonbi) = kite), a bird with a head inside of a rock.