Where to Watch 大雪海のカイナ (2023)

Summary

In another world, an ever-growing Sea of Snow has engulfed the planet surface. The people struggle to survive living around the routes of a massive Orbital Tree, whose branches spread into the Celestial Membrane high above the ground. Change comes to this dying world after Kaina, a boy from the Celestial Membrane, encounters a girl from the surface called Ririha.