Living in harmony with nature through stream fishing! Koharu and Hiyori, who became 'sisters' through their parents' remarriage, share their time fishing with Hiyori's childhood friend Koi and the Fukumoto sisters who run a boat. Starting with sea fishing and experiencing flatfish fishing, the two finally (?) take on the challenge of stream fishing, which can be called the pinnacle of fly fishing…? The girls' story connected by fishing lines, Volume 3!