A few millennia ago there were two separate realms: the demon realm and the human realm. Something happened and this led to the collision of the two realms and they later combined into one. There was an empire in each realm and now since the two realms have combined, the two races are fighting for supremacy.

The demons have superior physical abilities that they can take on 100 humans with only a dozen demons and they also have a longer lifespan than humans but because of their lifespan, they have less population. While humans may not be physically strong as the demons, but they have better weapons and armors, and the human army is trained to fight in formations.

The war between humans and demons have been going on since the realms collided and have not stopped since. And this war is known as 'The Eternal War'.