Amidst the glimmer of neon lights, technological advancement causes humans to be consumed by commercial convenience. In the shadows, a war between Yatagarasu and the Phantom Society is brewing, Devil Summoners who harness the otherworldly powers of “Demons”.

Existing in the secret sea of humanity's data, a digital hivemind has evolved into sentience: Aion. Observing humankind from afar, Aion calculates that a world-ending disaster is imminent and creates two agents to combat it: Ringo and Figue.

Together, these agents of Aion must investigate and prevent a butterfly effect that will lead to the end of the world.