Deava is an organization in a far-off future that confronts the dangerous "Shadow Angels." These beings have existed for over 12,000 years with a single goal: to annihilate humanity. Apollo, an unassuming human on the surface, is actually the rebirth of Apollonius, a fallen Angel. Alongside his allies, Apollonius must battle Touma, a Shadow Angel, to save the planet from its imminent demise.