Demons are a race of beings from the Demon World. They usually share appearances with humans but there are some slight differences. One of those is that most of the demons seen so far have green eyes.
Demons for the most part are stronger than humans, with special abilities depending on the class. Their power is shown through a black aura that emits from their body, almost like ink splashes. However there do exist numerous types of demons, with some being stronger than most demons and others being even weaker than humans. The weakest type of demons are unable to produce a physical body and are simply formless black mist that can only posses inanimate objects or weaker beings and other less weaker ones cannot be seen by humans. There are also demon beasts which reside in the Demon World and are wild instinct driven beings like animals in the human world.
- Weak Demons have often come to the human world in ancient times in order to escape persecution from stronger demons, such as Koma who was part of a weak tribe of demons who were exiled to the human world after losing a war, but they managed to gain the worship of humans and were considered purifying deities. Weak demons have also been the cause for the legends of ghost possessions and many of the monsters in ancient times. 
- Demons have their own way of saying grace before eating, and it consists of some sort of ritualistic dance to their gods.