ε Hellas

The worlds of Arcadia and Ostara sit upon a large expanse, a realm known as Hellas, or the Underground. It is most easily accessed by Ostara, making the population there inherently unaware that the beings of other races are not alien visitors from another planet (which is commonplace). 

The Underground is home to many of the demonae origin; a cursed diversity of races, created when the angels and deities of Heaven overturned their fellow bretheren and cursed them into damnation. The different array of curses led to deformities, which created the demonae races as a result.