Sometimes particularly wild and brutish humans are depicted as transforming into oni as they are warped by the foul energies surrounding them. Because they're Made of Evil (or at least Made of Chaos), supernatural powers used by oni are often classified as jujutsu ( 'hexes', 'maleficium' or 'witchcraft') even when they're overt or harmless. Under the Eastern Zodiac this is known as the 'ox-tiger' direction, so these forces came to be anthropomorphised as beings with features of oxen and tigers note Namely, horns as of the ox and tiger skins (in addition to tiger-like claws). 'Oni' originally referred to misfortune, bad vibes and evil spirits, which were traditionally said to come from the northeast. Which is consistent with their mythological descriptions. If some Oni are explicitly female, Bizarre Sexual Dimorphism may occur with males looking Gonky and the females looking more conventionally attractive. However, they won't always match the Red Oni, Blue Oni dynamics.

If Oni come in pairs, there's a good chance one will be red and the other blue. Others work jobs in Fire and Brimstone Hell as big red devils. Sometimes blamed for streaks of misfortune or violent weather. They are also shown to really love their alcohol, which can make them even more rowdy. They prefer huge bludgeoning weapons (iron clubs called kanabō being the most common) and hide loincloths (usually tiger-striped). They are sometimes depicted as good and sometimes as bad, but are usually morally neutral and interested in their own affairs rather than the usually outright malevolent ogres. Further, certain types are very calm and introspective, and female oni, being very beautiful, can get along well with (and sometimes marry) humans.

While still large, strong, and often brutish, Oni are known for possessing powerful magic and being far smarter than ogres. Contrary to the common mistranslation, Oni starkly differ from traditional depictions of Western ogres. The word is almost always translated into English as 'demons' or mistranslated (by tradition) as 'ogres'. Oni are brutish mountain Youkai superficially similar to Trolls and Ogres, with either one or two horns (which in some depictions are the source of their power). The Book of Yokai: Mysterious Creatures of Japanese Folklore

Oni x spirit