Youkai, Yokai or Ayakashi are paranormal beings originating from Japanese mythology. They are wide in variety and often take on unimaginable shapes and forms, though some Youkai even resembled humans in appearance.

In myths they were infamous for alien natures dangerous to humans and beyond normal understanding or comprehension varying from spirits of the dead to Possessed Objects and/or Deities and have since become a prominent part of Western culture as well. While not all Youkai are evil necessarily, they commonly appear as villains in both old folk tales and modern works.