Kitsune / Huli jing / Kumiho -
Mostly found in Japanese mytholgy (Kitsune), shape-shifting fox spirits are also found in Chinese (Huli jing) and Korean (Kumiho). Kitsunes are spirits who serve as messengers of the gods and play tricks on humans. They can usually be sorted into two types; Zenko, who are benevolent celestial foxes, and Yako, who are mischievous and sometimes malicious. In all versions of the story the fox spirit can take the form of a human. The Japanese kitsune does this by placing a leaf or skull on its head, while the Korean kumiho needs to eat human flesh in order to change its shape and the Chinese huli jing needs to absorb energy from either human breath or the moon and sun. All three versions have been known to trick people while in disguise and their favourite form is that of a beautiful woman. In the case of the kitsune it can not only take human form but it can also copy any living human. Kitsune have also been known to feed off human life force like a succubus through sexual contact while in human form.
Shape-shifting is not the only ability that these foxes possess. All of them have magical powers, superior intelligence and can live for thousands of years. The kitsune is the version with the most abilities, including: the ability to hear anything anywhere once they gain nine tails, producing fire from their tails and mouth, flight, the ability to summon and control lightening, invisibility, creating illusions, bending space and time, the ability to drive people insane, being able to turn into other objects including the moon, and, finally, possession. While possessed by a kitsune a person will be driven mad. They will yelp and scream like a fox, they will only eat foods that foxes like, froth at the mouth, run around naked and possess knowledge that they did not have before they became possessed. Illiterate people who have been possessed by foxes have been known to suddenly gain the ability to read and write in several languages.
A person who is actually a fox in disguise is rather easy to uncover. In some cases they do not hide their transformation very well. Their skin might be covered with a thin layer of hair, their faces might have narrow and fox-like features, and in some cases they might not be able to hide their tails. This usually becomes more obvious when they get drunk while in human form. They are also frightened of dogs. A person who is really a fox will quickly turn back into their fox form and flee if they are around a dog. An exorcism at an Inari shrine should coax a fox spirit to leave a possessed person.