An oni (鬼おに) is a kind of yōkai, demon, ogre, or troll in Japanese folklore. 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 or white-colored, wearing loincloths of tiger pelt, and carrying iron kanabō clubs. This is a symbol of the dark side. They are popular characters in Japanese art, literature, and theatre, and appear as stock villains in the well-known fairytales of Momotarō (Peach Boy), Issun-bōshi, and Kobutori Jīsan. 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 loincloths and carrying iron clubs called kanabō (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 be any number of 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.