Rin Matsuoka has been chasing after his late father's dream of becoming a world-class competitive swimmer.Rin has special feelings towards relay races, which his father also swam. However, due to differing opinions, he has a falling out with Sosuke, his best friend, and good rival. In time, Rin decides to go to a new team in order to swim the ultimate medley relay race.Rin departs for Australia, searching for something better.There, he experiences bitter defeat and sees first-hand the difference of ability between himself and the world. He returns home and hones his abilities at Samezuka Academy, becoming a key player in the team.During spring of his 3rd year in high school, he is suddenly reunited with Sosuke.While Rin is happy to be able to swim on the same team again, Sosuke has yet to tell anyone the real reason why he wants to spend his last year of high school at Samezuka Academy....A story about Rin, as he swims straight towards his dream while facing the "promise" he made to his one and only best friend.
