Modern Japan.

Guest was a genius pianist who dominated numerous domestic and international competitions, garnering attention from around the globe. However, after developing sudden sensorineural hearing loss and falling into the unlucky one-third whose condition never improves, they lost hearing in one ear. While still capable of performing, the perfectionist Guest could not accept a self that could no longer produce the same sound as before, and one day, they vanished from the music world without a word.

The one who chased after Guest more than anyone else is Hibiki Takanashi, a young pianist who built his skills through sheer hard work. The two have been acquaintances since Guest's active days, existing as rivals who mutually respected one another. Unable to forget the Guest who suddenly disappeared, Hibiki still listens to recordings of their performances over and over.

By chance, the two end up in the same high school class. Reunited, they begin to move their frozen time forward while confronting their respective inner conflicts—all to make a serenade echo once more through the silent night.