Well lets look at it in folklore

Supernatural powers commonly attributed to the Kyuubi include, in addition to shapeshifting, possession, the ability to generate fire from their tails or to breathe fire (known as kitsune-bi, literally "foxfire"), the power to manifest in dreams, and the ability to create illusions so elaborate as to be almost indistinguishable from reality.

Some tales go further still, speaking of Kyuubi with the ability to bend time and space, to drive people mad, or to take such nonhuman and fantastic shapes as a tree of incredible height or a second moon in the sky. Occasionally they are ascribed a characteristic reminiscent of vampires or succubi — these feed on the life or spirit of humans, generally through sexual contact.

In Japanese folklore, the Kyuubi are often presented as tricksters — sometimes very malevolent ones. The trickster Kyuubi employ their magical powers to play tricks on people; those portrayed in a favorable light tend to choose as targets overly-proud samurai, greedy merchants, and boastful commoners, while the more cruel kitsune tend to abuse poor tradesmen and farmers or Buddhist monks.

Despite their role as tricksters, however, a Kyuubi will keep a promise it has given and will strive to repay any favor it owes. Occasionally a Kyuubi will take a liking to and attach itself to a certain person or household; as long as it is treated with respect, it will use its powers for the benefit of its companion or hosts. As yōkai, however, Kyuubi do not share human morality, and a Kyuubi who has "adopted" a house in this manner might, for example, bring its host "gifts" of money or items that are in fact stolen from the host's neighbors. Any household suspected of harboring Kyuubi therefore, tends to be treated with suspicion.

Kyuubi are also commonly portrayed as lovers. These love stories usually involve a young human male and a Kyuubi who takes the form of a woman. Sometimes the Kyuubi is assigned the role of seductress, but often these stories are romantic in nature. Such a story usually involves the young man (unknowingly) marrying the fox, and emphasizes the devotion of the fox-wife. Many of these stories also possess a tragic element — they usually end with the discovery of the fox, who then must leave her husband. On some occasions, the husband wakes, as if from a dream, to find himself far from home, filthy, and disoriented, and must often return to confront his abandoned human family in shame.

Many stories tell of fox-wives bearing children. Such progeny of human-Kyuubi marriages are always human, but they are generally held to possess special physical and/or supernatural qualities, which are often passed to their children in turn. The specific nature of these qualities, however, varies widely from one source to another.

Kitsunetsuki (also written kitsune-tsuki) literally means the state of being possessed by a fox. The fox was believed to enter the body of its victim, typically a young woman, beneath her fingernails or through her breasts. In some cases, the victim's facial expressions were said to change in such a way that they resembled foxes. Japanese tradition holds that the possession can cause illiterate victims to temporarily gain literacy.

Victims of kitsunetsuki were often treated cruelly in hopes of forcing the fox to leave. It was not unusual for them to be beaten or badly burned. On some occasions, entire families were ostracized by their communities after a member of the family was believed to be possessed.

So how many things about Naruto has done to prove that it's based on this?