Hiyori likes to spend her times alone fly fishing. One day, a very energetic girl named Koharu tries to jump into the cold ocean in front of Hiyori and she stops her. This ends up being the beginning of their very unique relationship.
Koharu meets Hiyori's childhood friend Koi, who works at a fishing shop. Hiyori arranges a trip to a designated fly fishing location for Koharu.
Hiyori, Koharu, and Koi go on a fishing and camping trip with their families.
Koharu gets frustrated by Hiyori trying to help her so much as she's fishing and Koi celebrates her sixteenth birthday.
The girls go fishing on Ichika's boat and invite Futaba to come with them. Later, they all enjoy a nice meal at Hiyori and Koharu's house.
The girls go on a boat to try to catch some dorados for the first time and meet one of Ichika's friends.
The girls work on summer homework and Futaba comes over. She's nervous about telling her friend that she likes fishing, so they come up with a plan to see if she should tell her friend or not. Later on, the girls go fly fishing at a mountain stream.
Hiyori, Koharu, and Hinata go visit Hiyori's grandparents and the girls go fly fishing at a mountain stream.
Koharu tries to convince her dad to let her go on a fishing and camping trip with just Koharu and Koi, which causes a disagreement in the family, and results in Koharu and Hiyori running away from home.
Hiyori and Koharu get ready for their school's cultural fair and Hiyori goes fishing with Futaba.
All of the girls finally go on their autumn fishing and camping trip, and Koi thinks back on the past.
Koharu's birthday is coming up and the girls try to figure out what to get her. Meanwhile, the girls learn how to tie some flies.