Between being an exceptional student and taking care of the house alone during her mother's absence, Asuna Watase's only distraction is listening to her old crystal radio in her secret mountain hideout. One day, she accidentally tunes to a mysterious and melancholic melody, different from anything she has ever heard before. Soon after, an enigmatic boy named Shun saves her from a dangerous creature, unknowingly dragging Asuna on a long journey to a long-lost land bound to surpass her very imagination, turning her once melodic life into an intricate requiem.