The Oni (鬼) are horned, ogre-like creatures inhabiting the netherworld realm of Yomi (which is associated with but separate from Ama).^[1]

Given Hercules suspected a monster in disguise to be possibly an Oni (among other possibilities),^[3] it is possible that they possess either shapeshifting or illusion capabilities.

Oni-Makoto (Earth-7642), Oni Yew (Earth-2301)

• The Oni are creatures from Japanese mythology and folklore, roughly equivalent to the ogres and trolls from European folklore traditions. "They are typically portrayed as hulking figures with one or more horns growing out of their heads." They are typically depicted as having blue skin, green skin, or red skin. Their clothing is portrayed as consisting of loincloths created out of animal pelts. Their weaponry is portrayed as consisting of iron clubs. They are popular characters in Japanese fiction, often as stock villains.