There was a time when humans and demons lived together in peace. It all changed the day that human decided to attack and the peaceful bond was broken. Years after the destruction of Tartarus Sanctum and the elimination of Reaper's Apprentices, humans and demons are at each other's throats. To counter the problem, groups of demon slayers are rising to save the world. The war is brewing underneath, and people are becoming more aware of it.

In the midst of it all is DS461, four young men who are trying to move on with their lives after a tragedy. They started out young and became good enough to fight in the field at an early age. As trained demon slayers, they are waiting for a big adventure to come. They have sworn revenge on those that did them wrong and promise to get it at all costs. Then one night, after a failed mission, they come across four unlikely allies; a group of female demons. These demons make a deal with them; they do one favor for the demons and DS461 can have anything they want. All they have to do is agree to the terms.

Without thinking much, DS461 agrees. They don't know it now but they are about to set on the biggest adventure of their lives. It isn't over for either side. In fact, they've barely begun.