|Planet of Origin||Otherworld|
They generally have ogre-like form, horns, and red or blue skin. They also appear dressed like a business men and wear tiger-skin ties and pants. In the anime, unlike the oni work at Enma's castle, the guardians for Hell both wear a sort of gym outfit.
In Buddhist mythology, Yama, the King of Hell is assisted by oni, who help him punish sinners in Hell.