An oni (鬼) is a kind of yokai, demon, orc, ogre, or troll in Japanese Folklore, Oni are mostly known for their fierce and evil nature manifested in their propensity for murder and cannibalism. Notwithstanding their evil reputation, Oni possess intriguingly complex aspects that cannot be brushed away simply as evil. They are typically portrayed as hulking figures with one or more horns growing out of their heads. Stereotypically, they are conceived of as red, blue, black, yellow, or white-colored, wearing loinclothes of tigerpelt, and carrying iron kanabo clubs. They are creatures which instill fear and feelings of danger due to their grotesque outward appearance, their wild and sometimes strange behavior and their powers.
Depictions of yokai oni vary widely but usually portray them as hideous, gigantic ogre-like creatures with a single horn or multiple horns emerging from their heads, with sharp claws, wild hair, and fang-like tusks.
They are often depicted wearing tiger-skin loinclothes and carrying iron clubs called kanabo (金棒). This image leads to the expression “oni with an iron club” (鬼に金棒, oni-ni-kanabō), that is, to be invincible or undefeatable.
Their skin may have various colors, but red, blue, and green are particularly common. They may sometimes also be depicted as black-skinned, or yellow-skinned.
They may occasionally be depicted with a third eye on their forehead, or extra fingers and toes.
They are predominantly male but can be female. Females becoming oni has been attributed to them being overcome with grief or jealousy.
Oni can come in many different sizes ranging in both weight and height.
In Traditional Japanese Culture.
The traditional bean-throwing custom to drive out oni is practiced during setsubun festival in February. It involves people casting roasted soybeans indoors or out of their homes and shouting “Oni wa soto! Fuku wa uchi!” (“鬼は外！福は内！”, “Oni go out! Blessings come in!”), preferably by a strong wrestler. This custom has grown from the medieval ritual of tsuina (追儺, Chinese: nuo 儺) or oni-yarai, a year-end rite to drive away oni (ghosts).
Regionally around tottori prefecture during this season, a charm made of holly leaves and dried sardine heads are used as a guard against oni.
There is also a well-known game in Japan called oni gokko (鬼ごっこ), which is the same as the game of tag that children in the Western world play. The player who is “it” is instead called the “oni”.
In modern Japanese Culture.
In more recent times, oni have lost some of their original wickedness and sometimes take on a more protective function. Men in oni costumes often lead Japanese parades to dispel any bad luck, for example.
Japanese buildings sometimes include oni-faced roof tiles called onigawara (鬼瓦), which are thought to ward away bad luck, much like gargoyls in Western tradition.
Many Japanese idioms and proverbs also make reference to oni. For example, the expression “Oya ni ninu ko wa oni no ko” (親に似ぬ子は鬼の子) (Translation: “A child that does not resemble its parents is the child of an oni.”) may be used by a parent to chastise a misbehaving child.
They can be used in stories to frighten children into obeying because of their grotesque appearance, savage demeanor, as well as how they can eat people in a single gulp.