As for why they're so popular in anime, it's simply a matter of how important they are in classical Japanese mythology. Kitsune are associated with Inari, a rice and fertility god, making them important symbols for a society once dependent on farmers' harvest.
In Edo period literature, the most common type of kitsune are nogitsune, which roughly translates to “wild foxes.” Like their wiser, holier counterparts, the tenko, they can transform into humans.
In yokai (ghost story) folklore, kitsune evolve greater abilities as they age. Natural shapeshifters, they are believed to be able to take human form after they have reached their hundredth year. Evil foxes, known as nogitsune, are wild creatures that serve no god and carry no divinity within their souls.
Kitsune is often portrayed as mischievous and known for playing tricks on humans. However, it can also be seen as a symbol of good fortune, particularly in the Shinto religion from Japan.
Shapeshifting: Kitsunes are able to shapeshift themselves into other forms. Kitsunes can either make themselves an older version of themselves or even a younger version as well as changing their height and weight. They can even change their gender to that of the opposite one if they so please.
As the number of tails indicates the level of wisdom and magical prowess, the nine-tailed fox is considered especially powerful. Tamamo-no-Mae is one such nine-tailed fox, or Kyubi no kitsune, of particular note.
The lifespan of a kitsune depends strongly on the number of tails they have, with one tailed individuals living 75 years or so, while those with multiple tails can live well into their second century and beyond.
Canidae: Kitsunes are known to have a great fear and hatred of dogs and wolves. Some become so rattled by the presence of that they will revert to the shape of a fox and flee.
Japanese Kitsune Romance
There are many stories in Japanese folklore of kitsune falling in love with a human man and choosing to live out their lives in the human world. Most of the stories follow the same pattern: a young man falls in love with a beautiful fox lady, and they marry, unaware of the fox's real identity.
Depending on the circumstances, kitsune can help or harm humans. In most stories, an evil fox (Yako) takes the form of a woman so as to manipulate powerful men.
Other kitsune have characteristics reminiscent of vampires or succubi and feed on the life or spirit of human beings, generally through sexual contact.
Are Kitsunes flirty? Though kitsune may flirt or seduce their prey to get closer to them, it is preferred if they feed only off the wicked or have a willing partner.
Kaze Kitsune
These kitsune are incredibly rare and are said to bring good luck to those who find them.
Tamamo-No-Mae, The Kitsune Queen.
In Japanese mythology, there are said to be 13 types of kitsune, which correspond to different elements—celestial, wind, spirit, darkness, fire, earth, river, ocean, forest, mountain, thunder, sound, and time. Broadly, they can also be broken into two groups—zenko, or good, and nogitsune, or bad.
A foxes disguise is not perfect and there are ways to tell if a person is actually a kitsune in disguise. Characteristics of its true self may shine through such as a fine coat of fur, a fox-shaped shadow, and even a reflection revealing it's true form.
Kitsune have a fear and hatred of dogs even while in human form, and some become so rattled by the presence of dogs that they revert to the shape of a fox and flee.
Foxes are said to be terrified of dogs because dogs aren't fooled by illusions. They will bark and let everyone know what's up, sometimes even causing the fox to lose its human form. Dogs were also even used in cures for possession: Smear fish paste all over the victim and have a dog lick it off.
Superhuman Durability - Kitsune are invulnerable to any form of harm. They can only die if they're stabbed in the heart, or starvation. Longevity - Kitsune have an extended life span. Some have been know to be as old as 900 years of age.
Kitsunes are born with a single tail which is considered smaller and thinner than a normal fox tail, this tail will naturally grow over time developing into a full foxtail by the time they are in their first 15 years of their life, then eventually by the time they reach the age of 100, it will be fully developed into a ...
Size: Kitsune are about the same size as humans, ranging from 5 to 6 feet tall.
Other supernatural abilities commonly attributed to kitsune include possession, generating fire or lightning, willful manifestation in the dreams of others, flight, invisibility, and the creation of illusions so elaborate as to be almost indistinguishable from reality.
Inari Ōkami (Japanese: 稲荷大神), also called Ō-Inari (大稲荷), is the Japanese kami of foxes, fertility, rice, tea and sake, of agriculture and industry, of general prosperity and worldly success, and one of the principal kami of Shinto. In earlier Japan, Inari was also the patron of swordsmiths and merchants.
In kitsune lore, once a fox reaches the age of 100, they gain the power of shapeshifting. The fox grows a new tail every century until they have nine, and the color of their fur will eventually change from red to gold and finally to white (Geller).