Nearly 700 years ago, a deal was made between a human lord, Oh Sehun, and the archangels of Heaven. In exchange for the revival of his beloved, Luhan, Sehun was to die and be reincarnated. In their next life, Luhan and Sehun were to become the angels' "human vessels" and recieve powers beyond imagination, fueled by their joined soul, one forged by God himself.

The downside?

These supernatural abilities had to be used to fight off the Demon Kings and their soldiers, who were preparing for an all-out invasion of Earth.

Oh, and the demons' first order of business: kill any that opposed them. Especially the angels' vessels