Within a future era marked by advanced technology and looming threats, in a world where humanity faces existential peril, Deava is tasked with confronting the Shadow Angels—creatures that have survived for more than 12,000 years and whose sole mission is to annihilate humanity. Apollo appears as an ordinary person but is actually the rebirth of a fallen Angel, Apollonius, who once battled Touma, a Shadow Angel, along with allies to avert Earth"s destruction for future generations.