Apparently, this game really does take place in the same world as God Eater, judging by how that cameo of an Aragami is part of the main story, and not just some DLC buggery.
Like, the God Eaters had to inject themselves with the Oracle Cells that caused this whole mess just to survive and fight them off, and are constantly hoping that the Bias Factor doesn't fail and their own weapon doesn't devour them while fighting what is essentially a Grey Goo Ecology.
While the Revenants had to inject themselves with the parasites that seem to have caused this whole mess just to survive, and are constantly hoping that they get enough blood and will to not become horrible immortal monsters, while fighting against a combined zombie apocalypse, vampire apocalypse, mutant apocalypse and asshole apocalypse.
Holy shit is the world of God Eater/Code Vein fucked.