Nakaba Sakura is a tomboyish middle school girl who excels at sports and hates to lose. Years earlier, she used to play piano duets with her childhood friend and neighbor, Haru, and the two shared a special bond over a Chopin piece that became their secret song. When Haru moved away to another city, Nakaba lost all motivation to continue piano. She found reading sheet music frustrating—the notes looked like meaningless dots on the page—and she had struggled to enjoy formal lessons. She quit playing entirely.

Six years later, Haru suddenly transfers back and enrolls in the same school as Nakaba. He seeks her out immediately, still wanting to play their secret duet together and even pressuring her to perform in an upcoming contest. Nakaba is caught off guard: she has not touched a piano in years, and the Haru who returns is not the gentle, kind boy she remembers. He seems more distant and driven, and his insistence reopens old wounds. Forced to confront her abandoned passion and the changes in their relationship, Nakaba must decide whether she can rediscover the joy of playing and whether she is willing to meet Haru on the piano bench again, even as their history and unspoken feelings complicate every note.