Long ago, in a world parallel to our own, humans lived in constant fear of the nocturnal beasts that we only know as demons. Living under the protection of the angels, it seemed like the world was living in peaceful tension. However, when the demons finally took control, nearly wiping out any and all creatures that could stand up to them, they ruled the realms with an iron fist. Angels were scarce and anyone who descended from them were walking targets or became slaves to the demons. After generations of preparation and determination, an organization known as the Haven finally established an elite group called the Guardians to fight against the ever-growing population of demons.