Ooyukiumi no Kaina

Humanity survives on scattered patches of land beneath enormous Orbital Trees, surrounded by a vast Snow Sea and facing a worsening shortage of water. Princess Ririha of Atland climbs to the translucent Canopy high above the surface seeking a legendary sage who might know how to save her country. Instead she meets Kaina, a young man who believed almost no humans remained below.

Unable to return alone, Ririha brings Kaina down into a world he has never seen. There he discovers Atland locked in a desperate conflict with the mobile nation of Valghia over dwindling resources. The old legends that brought Ririha to the Canopy may contain more truth than either expected, and Kaina's journey across snow, sea, and sky becomes tied to finding a future for people who are running out of the one thing they cannot live without.