Kitsune are from Japanese folklore and are Japanese foxes. A kitsune can have up to nine tails, depending on its age, wisdom and power. The only way to kill a kitsune is to cut off all of its tails, as it is said that one of the tails is its main tail and the source of all its power. Not knowing which tail is the main one, one would have to cut off all its tails to kill it.One, five, seven, and nine tails are the most common numbers in folk stories. When a kitsune gains its ninth tail, its fur becomes white or gold.
A kitsune is a shapeshifter, and usually when it reaches the age of 100 years, it learn the ability to take on a human form. Thus, they have to be a fox for a hundred years before it can shapeshift from a fox to a human and back again. It is also said that a kitsune can duplicate other human beings, in other words shapeshift into the look-a-likes of different people.
Kitsune can be either male or female, and usually take the form of young Japanese girls, beautiful women and older men.
Kitsune are believed to possess superior intelligence, long life, and magical powers. They are a type of spiritual entity, and the word kitsune is often translated as fox spirit. However, this does not mean that kitsune are ghosts, nor that they are fundamentally different from regular foxes. Because the word spirit is used to reflect a state of knowledge or enlightenment, all long-lived foxes gain supernatural abilities.
There are two common classifications of kitsune. The zenko (善狐, literally good foxes) are benevolent, celestial foxes associated with the god Inari; they are sometimes simply called Inari foxes. On the other hand, the yako (野狐, literally field foxes, also called nogitsune) tend to be mischievous or even malicious. Local traditions add further types. For example, a ninko is an invisible fox spirit that human beings can only perceive when it posseses them. Another tradition classifies kitsune into one of thirteen types defined by which supernatural abilities the kitsune possesses.
Physically, kitsune are noted for having as many as nine tails. These kyūbi no kitsune (九尾の狐, nine-tailed foxes) gain the abilities to see and hear anything happening anywhere in the world. Other tales attribute them infinite wisdom (Omniscence).
There are thirteen different kinds of Kitsune, each with a corresponding element, listed as follows: Heaven (or Celestial or Prime), Void (or Dark), Wind, Spirit, Fire, Earth, River, Ocean, Mountain, Forest, Thunder, Time and Sound. One of the most important things to a Kitsune is freedom. They do not fare well to being locked away, and do not like to be forced to do something they don't want to. Doing something like that would be likely to get you killed if they are freed. Kitsune love playing tricks. They like to take things and hide them from people, or do just about anything else to piss someone off.
Kitsunes' have things called Kitsune balls, or star balls, which is a small white-gold ball that is a Kitsune's most prized 
possession, since it is almost like their life force in a ball. If you get your hands on a Kitsune's star ball, you would have the ability to control the Kitsune, and make it do your bidding. However, Kitsune hate being stripped of their freedom, and when the Kitsune gets its star ball back, there will be serious repercussions for you to deal with.
In some stories, kitsune have difficulty hiding their tails when they take human form; looking for the tail, perhaps when the fox gets drunk or careless, is a common method of discerning the creature's true nature. Variants on the theme have the kitsune retain other foxlike traits, such as a coating of fine hair, a fox-shaped shadow, or a reflection that shows its true form. Kitsune-gao or fox-faced refers to human females who have a narrow face with close-set eyes, thin eyebrows, and high cheekbones. Traditionally, this facial structure is considered attractive, and some tales ascribe it to foxes in human 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. A particularly devout individual may be able to see through a fox's disguise automatically.
One folk story illustrating these imperfections in the kitsune's human shape concerns Koan, a historical person credited with wisdom and magical powers of divination. According to the story, he was staying at the home of one of his devotees when he scalded his foot entering a bath because the water had been drawn too hot. Then, "in his pain, he ran out of the bathroom naked. When the people of the household saw him, they were astonished to see that Koan had fur covering much of his body, along with a fox's tail. Then Koan transformed in front of them, becoming an elderly fox and running away."
Other supernatural abilities commonly attributed to the kitsune include possession, mouths or tails that generate fire or lightning (known as kitsune-bi; literally, fox-fire), willful manifestation in the dreams of others, flight, invisibility, and the creation of illusions so elaborate as to be almost indistinguishable from reality. Some tales speak of kitsune with even greater powers, able to bend time and space, drive people mad, or take fantastic shapes such as a tree of incredible height or a second moon in the sky. Other kitsune have characteristics reminiscent of vampires or succubi and feed on the life or spirit of human beings, generally through sexual contact.
Kitsunetsuki
Kitsunetsuki (狐憑き or 狐付き; also written kitsune-tsuki) literally means the state of being possessed by a fox. The victim is always a young woman, whom the fox enters beneath her fingernails or through her breasts. In some cases, the victims' facial expressions are said to change in such a way that they resemble those of a fox. Japanese tradition holds that fox possession can cause illiterate victims to temporarily gain the ability to read. Though foxes in folklore can possess a person of their own will, Kitsunetsuki is often attributed to the malign intents of hereditary fox employers, or tsukimono-suji.
Exorcism, often performed at an Inari shrine, may induce a fox to leave its host if it is possessing someone. In the past, when such gentle measures failed or a priest was not available, victims of kitsunetsuki were beaten or badly burned in hopes of forcing the fox to leave. Entire families were ostracized by their communities after a member of the family was thought to be possessed.
In Japan, kitsunetsuki was noted as a disease as early as the Heian period and remained a common diagnosis for mental illness until the early 20th century. Possession was the explanation for the abnormal behavior displayed by the afflicted individuals. In the late 19th century, Dr. Shunichi Shimamura noted that physical diseases that caused fever were often considered kitsunetsuki. The belief has lost favor, but stories of fox possession still appear in the tabloid press and popular media. One notable occasion involved allegations that members of the Aum Shinrikyo cult had been possessed.
In medicine, kitsunetsuki is an ethnic psychosis unique to Japanese culture. Those who suffer from the condition believe they are possessed by a fox. Symptoms include cravings for rice or sweet red beans, listlessness, restlessness, and aversion to eye contact. Kitsunetsuki is similar to but distinct from clinical lycanthropy.
Tricksters
Kitsune are often presented as tricksters, with motives that vary from mischief to malevolence. Stories tell of kitsune playing tricks on overly proud samurai, greedy merchants, and boastful commoners, while the crueler ones abuse poor tradesmen and farmers or devout Buddhist monks. Their victims are usually men; women are possessed instead. For example, kitsune are thought to employ their kitsune-bi or fox-fire to lead travelers astray in the manner of a will o' the wisp. Another tactic is for the kitsune to confuse its target with illusions or visions. Other common goals of trickster kitsune include seduction, theft of food, humiliation of the prideful, or vengeance for a perceived slight.
Kitsune keep their promises and strive to repay any favor. Occasionally a kitsune attaches itself to a person or household, where they can cause all sorts of mischief.
Other kitsune use their magic for the benefit of their companion or hosts as long as the human beings treat them with respect. As yōkai, however, kitsune do not share human morality, and a kitsune who has adopted a house in this manner may, for example, bring its host money or items that it has stolen from the neighbors. Accordingly, common households thought to harbor kitsune are treated with suspicion. Oddly, samurai families were often reputed to share similar arrangements with kitsune, but these foxes were considered zenko and the use of their magic a sign of prestige. Abandoned homes were common haunts for kitsune. One 12th-century story tells of a minister moving into an old mansion only to discover a family of foxes living there. They first try to scare him away, then claim that the house "has been ours for many years, and . . . we wish to register a vigorous protest." The man refuses, and the foxes resign themselves to moving to an abandoned lot nearby.
Tales distinguish kitsune gifts from kitsune payments. If a kitsune offers a payment or reward that includes money or material wealth, part or all of the sum will consist of old paper, leaves, twigs, stones, or similar valueless items under a magical illusion. True kitsune gifts are usually intangibles, such as protection, knowledge, or long life.
Wives and lovers
Kitsune are commonly portrayed as lovers, usually in stories involving a young human male and a kitsune who takes the form of a human woman. The kitsune may be a seductress, but these stories are more often romantic in nature. Typically, the young man unknowingly marries the fox, who proves a devoted wife. The man eventually discovers the fox's true nature, and the fox-wife is forced to leave him. In some cases, the husband wakes as if from a dream, filthy, disoriented, and far from home. He must then return to confront his abandoned family in shame.
Many stories tell of fox-wives bearing children. When such progeny are human, they possess special physical or supernatural qualities that often pass to their own children. The astrologer-magician Abe no Seimei was reputed to have inherited such extraordinary powers.
Other stories tell of kitsune marrying one another. Rain falling from a clear sky — a sunshower — is called kitsune no yomeiri or the kitsune's wedding, in reference to a folktale describing a wedding ceremony between the creatures being held during such conditions.The event is considered a good omen, but the kitsune will seek revenge on any uninvited guests.
(Please go and check out the wikipedia page on the kitsune! It's really interesting! Also, that is where I got most of my info, so I don't own anything.)