Hoshi wo Ou Kodomo

A strange song heard through her late father's crystal radio leads Asuna toward an encounter with Shun, a boy from the underground world of Agartha. Their brief friendship ends in his sudden disappearance, leaving her with a longing she cannot explain. When his lookalike Shin appears alongside her teacher Morisaki, a path into that hidden world opens.

Morisaki hopes to recover the wife he has lost, while Asuna follows with questions about Shun and her own loneliness. Crossing Agartha's unfamiliar landscapes exposes them to its dangers and to the cost of seeking the dead. Their journey forces each to consider whether love means holding on or learning to say goodbye.