The story of the game is set in the distant mountain village of Okukozome-chō. Haruka Kazugano and his twin sister Sora have fond childhood memories of going to the village to visit their grandfather during their summer vacations. However, after losing their parents in an accident, the two must move in with their grandfather.
The twins get reacquainted with their old childhood friend Nao Yorihime, their new classmate Ryōhei Nakazato, the miko (shrine maiden) Akira Amatsume, and Akira's friend Kazuha Migawa. All seems peaceful and familiar. However, beneath the surface is a secret promise that the twins made with each other long ago, the whereabouts of an important lost item, and the real reason they chose to come back here.
Tragically orphaned by an automobile accident, the Kasugano twins travel to their grandparent’s countryside residence via railcar, hoping to reconstruct the shards of a shattered life. Future uncertain, Haruka Kasugano clings to memories of the past, hoping to find the strength he needs to safeguard his ailing sister. With a destiny irrevocably tied to that of another, Sora Kasugano clings to moments of the present, drawing comfort and security from the company of her brother. Two lonely souls so physically alike, yet spiritually divergent, unaware of the challenges these conflicting expectations will unveil in the days to come.