S1E04 Captive Butterfly!/Plot

The Iwatobi High School Swim Club officially starts training in the refurbished pool using an old training regiment that Gou Matsuoka has unearthed. Rei Ryugazaki's inherent academic skills at learning swimming theory prove to be useless since his body refuses to move in the water. Elsewhere, Rin Matsuoka grudgingly realizes that his victory against Haruka Nanase was due to Haruka's lack of physical training and not his actual talent. Nagisa Hazuki and Makoto Tachibana start teaching Rei how to swim and learn that while he can float, his problem remains.

The following day, the guys try to come up with designs for a club uniform, but Gou gives Rei's lessons higher priority and makes a revamped swimming regimen during which he must master swimming in one week before their first prefectural tournament. Nagisa and Makoto try and fail to teach Rei their signature techniques -- the breaststroke and backstroke, respectively -- causing Rei to blame his inability on their teaching methods.

Makoto suggests they ask Goro Sasabe for help, but he bluntly refuses. Over the weekend, Rei attributes his inability to swim to not having proper gear, hence prompting a visit by the team to a sports store to buy swimming essentials. At the store, Haruka and Rin run into each other and have a short discussion about their differing forms with Rin wanting a race with them both in peak condition, or else he may not be able to move forward. Both decide to settle the score at the upcoming tournament.

Afterwards, Haruka takes a turn trying to teach Rei freestyle swimming and fails, greatly disappointing Rei. As the day draws to a close, Haruka laments to Rei that he, too, isn't compatible with other techniques; he swims freestyle because it is all he can swim. The next day, Rei tries the last technique and finds it compatible with himself: the butterfly stroke.