Oni (鬼) are a sentient race that are a related to most other demons known for their incredible strength and manipulation of Fire. In the distant past oni were know to terrorize a large portion of eastern Asia going by different names in each region. While in base form they appear very human except small protrusions in the skull where their horns will appear can be found. It would appear that oni are able to assume a human form of their own choosing. When they assume their true demonic form their appearance in usually unique, and provides the oni with their own set of abilities. While the appearance of a transformed Oni can differ greatly between beings it is typical that the Oni's horns grow in length and shape. Some Oni even grow wings when they transform, but this seems to be limited to the strongest oni.
The Oni have a developed a hierarchy over their long years of existence. This hierarchy takes the form of a two class system consisting of the Royal Family and the Grunts. While it would seem that Royal Family suggests the a noble heritage it is merely the spawn of the most powerful oni at the time. If a powerful enough oni is able to overthrow the current king, they simply replace the royal family with their own children. While Oni do not call any one location home and instead set up occupations in the underworlds of large cities around Europe, Asia, and some of Northern Africa, they do boast a powerful army that will band together for a common cause.
Oni have the ability to hurl explosive fire from their hands and the ability to teleport short distances. They boost incredible durability even in their human guises, that is greatly increased in their truly demonic state. Despite their incredible abilities Oni are susceptible to heavy amounts of damage around and to their horns in both their human and demon forms. If for some reason a was to be completely removed the Oni would be in an incredible weakened state for quite some time as it regenerated. Oni have exceptionally long lives and are know to occasionally live for 500 years.