The Shinto and Buddist Oni were divided into two types:

1.From Hell, called :"Gaki".
2.From Earth (Oni)

GAKI are able to take a somewhat humanoid shape, but usually are not able to hide their huge swollen bellies. They are red or green and have the head of either a horse or an ox with three eyes and grotesque horns and talons.

They are constantly tortured with raging hunger and thirst.

They pounce upon the wicked who are close to die and send them to the torment of Hell.

ONI are earth demons who can shapeshift into a human form of a relative or aquaintance, of the person that they want to torment.

Some of these are rumoured to be the distorted souls of women who have died of excessive grief.
These demons are responsible for bringing misfortune,and disease - especially the plague.

They may be driven out during the "Shinto Oni-yarahi" ceremony.