The Silent Morning, August 22, 2015, marked the end of the world. At 8:30AM, without warning the world started to give way under people's feet, and a demonic invasion began, killing many of the inhabitants. After the event, everyone still alive lives on chunks of the shattered Earth, connected by a system of tunnels called "Trans-Cores". The citizens live in fear that everyday could be their last, due to the numbers of demons and zombies plaguing the planet. The only thing left standing in the way of the villainous horde is the Vake, a group of three (later four) color coded warriors that were "Blessed" with the abilities to draw energy from the plague races and make themselves stronger, but with the cost of having become undead, and the marks on their bodies growing with every kill, threatening to overtake their bodies and dragged off to hell.
Later on, however, it turns out that The Silent Morning was actually the product of a scientist named Dr. Kobiyashi, who, along with his aids, cast a spell on the entire planet to utterly destroy everything but his lab, the land around the lab and his aides, so that they can rebuild the world as he wants it. It then becomes the goal of the Vake: Hitoru, the Emerald Vake with a a coat that rivals Dante in awesomeness, Matsui, the Sapphire Vake, who acts very much like a kid until he gets to use his fists on something, Kinomaru, the Ruby Vake, who is brooding, blunt, but actually watched over the orphaned Ikiyo, the Amber Vake, a wolf demon who uses energy to fight and was shown to be one of the few good demons around, to stop Kobiyashi before he can complete his plan from going right all the way this time.