Suzu is a 17-year-old high-school student living in a rural town with her father. Wounded by the loss of her mother at a young age, Suzu one day discovers the massive online world "U" and dives into this alternate reality as her avatar, Belle. Before long, all of U's eyes are fixed on Belle, when, suddenly, a mysterious, dragon-like figure appears before her.

Eiko grows up through the seasons, navigating a series of encounters with sound and people. Her journey intertwines her professional work as a piano tuner with vivid sensory memories of her past.

A boy rescues a girl who has collapsed in a river, from their exchanges and memories a tale of loneliness and meaningful connection gradually unfolds.

This is the first work in the "River" series, born from Sasaki's idea that "music was born on the banks of the river." The lives of people living on the banks of the river are depicted through "sounds" such as the bells and violins that ring through the town. The story is set in Cremona, a town on the banks of the Po River in northern Italy. A-san, a tuner, deepens her ties with the people living in the Po River basin while repairing broken violins.

Third in the River series. Piano tuner Eiko travels up the Danube River. In the ancient city of Bratislava, where Mozart's melodies flow, she encounters the sound of shepherds calling forth spring from the earth with their long whips, the echoing sound of the fujara flute in the mountains and fields, and a music box playing memories... Eiko meets the kind-hearted people of Slovakia and the vibrant sounds of spring.

Second in the River series. Piano tuner Eiko visits a town on the banks of the Guadalquivir River in Andalusia, Spain. In the dazzling light, she interacts with the people of Andalusia—a master guitar maker, a cave excavator, and a flamenco prodigy—and spends a summer surrounded by the sounds they create.