Gate of Darkness
The Gate of Darkness is a portal which the dark god Mardük opened during the final battle of the Great War. It links directly to the Demon Realm from which demons can enter the world of mortals. When the Godslayer devoured Mardük, no one had enough dark powers to close the gate down. The gate remains open even to this day, letting more and more demons enter Yamato to reinforce the demon hordes.