The Amanojaku or Amanjaku ("heavenly evil spirit") is a demon-like creature in Japanese folklore.

In folklore

It is described to be a being with an extremely contrary nature: If they were ordered something, they would do the opposite. It is thought to be able to provoke a person's darkest desires and thus instigates them into perpetrating wicked deeds. It is usually depicted as a kind of small oni. One of the amanojaku's best known appearances is in the fairytale Uriko-hime (瓜子姫), in which a girl miraculously born from a melon is doted upon by an elderly couple. They shelter her from the outside world, and she naively lets the amanojaku inside one day, where it kidnaps or devours her, and sometimes impersonates her by wearing her flayed skin.

In religion

The amanojaku is commonly held to be derived from Amanosagume (天探女), a wicked deity in Shintō mythology, which shares the amanojaku's contrary nature and ability to see into a person's heart, "a very perverted demon". The creature has also entered Buddhist thought, where it is considered an opponent of Buddhist teachings, perhaps via syncretism with the yaksha. It is commonly depicted as being trampled on and subdued into righteousness by Bishamonten or one of the other Shitennō. In this context, it is also called a jaki (邪鬼).

In popular culture