Kaina of the Great Snow Sea - S01

Humanity is on the brink of extinction. The world is buried in snow, water is scarce, and the only habitable lands lie at the base of massive Orbital Trees dotting the barren Earth. A legend speaks of a sage who holds the secret to creating enough water to save mankind. Ririha, the princess of Atland, ascends an Orbital Tree in an organic hot-air balloon, hoping to find her people's savior. When she reaches the Canopy-a seemingly endless expanse of transparent ice-she encounters Kaina, one of the last men living there. But the sage she seeks is nowhere to be found. Stranded and unable to return home alone, Ririha accepts Kaina's help. He, in turn, is curious about the surface world he believed was lifeless. As Kaina learns of the war between Ririha's kingdom and the advanced nation of Valghia, along with other dangers below, he realizes guiding her back will be far harder than he expected.