Kaina of the Great Snow Sea

Overview

Kaina is the only youth in the last remaining village that clings to life on the Canopy, high above the surface of the world. When Liliha, a princess from the surface, makes her way to the Canopy, they both realize that there is more to their world than they knew. Kaina agrees to help Liliha return to the Great Snow Sea far below, where her kingdom is imperiled by the rapacious neighboring kingdom of Bargia. The trip is arduous, and foes lie in wait at the end of their descent. With Liliha taken prisoner and her father the king too caught up in politics to rescue her, Kaina has no choice but to set off with only the young prince in tow, braving the dangers of the Great Snow Sea to rescue Liliha from Bargia's clutches... (Source: Kodansha USA)

Source: AniList