In Japanese folk lore, the Oni is the demon associated with all kinds of evil and distressful emotions. These demons are said to lurk around the dying, rushing in to pull souls down to hell. In demon hierarchy, they are worse than the Tengu (the crow-like or long-nosed goblin mischief-maker), wreaking serious damage to humans and devastation to the land.

The Oni character appeared in mime and dance, and also in prayers for peace, fertility and longevity, customs that became an intricate part of the Japanese culture. In Buddhist rituals, monks and priests held retreats in order to dispel Oni from the land. In the traditional Japanese Noh theatre performances, the essence of the Oni character is displayed in each mask. The demon character usually appears at the end of the play, along with other non-human entities.