In a world where Avians live high above the clouds on floating islands, spirits dwell in the ruins left on the surface. The spirits strive to eat the life crystals hanging from the branches on the Tree of Life, causing the Avians great despair. The Avians formed an organization that specializes in dealing with these spirits called Guardian Arcs. A young boy named Gabriel has long dreamed of joining their ranks and becoming the most honorable Guardian Arc, but unfortunately his confidence and flying skills are below that of his peers. Gabriel teams up with Sela, Simeon, Royce, and Grigori on a quest into the forbidden ruins to investigate the uprising spirits.