There are two worlds; the world of Humans, and the world of Demons. The humans live in a world of technological advancement and freedom. The demons in a world of chaos and barbarism. 10 years ago, for an unknown reason, the demons invaded the human world, and slaughtered millions. However, the clashing of the two worlds' realities caused a strange reaction in the humans, granting some of them exceptional superpowers. With these powers, they fought back, and a decade long war ensued.