A creature from Japanese folklore. Usually translated as "demon" or "ogre".
Traditionally depicted with red or blue skin, a tiger print loincloth, and oni horns. Oni horns are long, smooth, skin-covered or otherwise the same color as the skin, and located on the front of the head. Their weapon of choice is the spiked club, particularly the kanabou. They are violent and favor brawn over brains. Save for the horns, modern depictions tend to mute these characteristics considerably or entirely, especially in female characters, only keeping their iconic dual horns intact.
Oni are commonly associated with Setsubun, a holiday taking place on February 3rd, the last day of winter in the traditional Japanese calendar. On this day it is tradition to throw roasted soybeans in order to drive away oni; this practice is known as mamemaki.