Second year high schooler, Haruka Nanase reminisces about his time spent with his friends in their grade school swimming club and of wanting nothing more than to be a freestyle swimmer. In the present, Makoto Tachibana goes to pick Haruka up for their second day of school at Iwatobi High, and while having lunch that day, they encounter their old friend, and recent transfer, Nagisa Hazuki. Nagisa not only wishes to swim with Haruka like they used to, but also suggests that dig up a time capsule containing a relay trophy they had won with their friend Rin Matsuoka at the dilapidated Iwatobi Swimming Club. While there, Haruka once again reminisces over a photo of the race, being the last time the group had swam together before Rin had moved to Australia to enroll in a swimming school. Afterwards, the group shockingly runs into a completely changed Rin in the hallways and immediately challenges Haruka to a race, until they discover that the old pool is empty. At school the next day, a scarlet-haired girl observes the group with a friend and remarks of them being old acquaintances before Makoto and Nagisa are reprimanded for trespassing at the swimming club. As Makoto and Nagisa visit Haruka that evening, they discover the scarlet-haired girl who turns out to be Rin's sister, Gō Matsuoka attempting to pay Haruka a visit and learn from her that Rin is now attending the Samesuka Academy upon his return from Australia. Afterwards, Makoto and Nagisa convince a reluctant Haruka to visit the academy by tempting him to a swim in the school's pool. Upon arriving, they wait after hours and break into the academy's swimming pool until they are discovered by Rin who aggressively orders them out. Haruka then steps out of the pool and challenges Rin to a freestyle race.