Demons are a race generally almost identical to humans, native to Meeriad's Nookiya region, but with demonic features such as claws, red eyes, and leathery, bat-like wings, though some have much stranger deviations in appearance. They are not, in fact, creatures of the underworld, but were deemed such in the early days of Meeriad because of their features.

Though possessing wings on their backs, demon bones are far too heavy for true flight, but they can glide varying distances depending on weather conditions.

Demons are in essence immortal. After reaching maturity, they stop aging completely and, if they avoid being killed by other means, can live forever. They are still susceptible to viral or bacterial infection, though to a lesser extent even than a healthy young human, as well as bodily injuries and nobody's luck lasts forever. (See "Average Lifespan")