Demon Gods are techno-organic weapons of mass destruction in the world of Bastard.
Demon Gods were created as the ultimate weapons during the last days of the Old World. Combining technology, magic, and living tissue, each was a thing of enomrous power and destructive might.
Eventually, the scientists of the Old World created one final Demon God, Anthrax, in order to force the end of all wars. As soon as it was completed, it became active and went out of control, summoning the other Demon Gods, and sending them out to destroy all of humanity.
With the defeat of Anthrax by the Dragon Knight, the Demon Gods went dormant.
When Anthrax awoke 400 years later, it also awoke the dormant Demon Gods. After Anthrax's defeat by Dark Schneider, Anthrax and the other Demon Gods were revealed to have been under the control of Angels.