There are two means to become a kitsune on the show. A kitsune can be born with their human heritage, inheriting their trait from one or more kitsune parents. They can also be a fox spirit originally that gains the ability to shapeshift into a human form supposedly after a 100 years.
Kitsune have a vast longevity, capable of living for up to hundreds of years. Some kitsune are known to fully transcend their mortal lives, becoming fully immortal.
There are 13 kinds of kitsune. Five have appeared or mentioned as canon on the show: celestial, earth, ocean, thunder and void. The remaining eight types are listed as non-canon: fire, forest, mountain, river, sound, time, spirit and wind.
Series
Kira Yukimura is a teenage kitsune, of the type Thunder, introduced in Season 3. Kira discovers her latent powers, strives to learn how to control and use them. She forges her first Tail as a shuriken and becomes a member of Scott's Pack. Noshiko Yukimura, Kira's mother, is a Celestial kitsune, close to 900 years old and serves as Kira's mentor. An immortal Void Kitsune, an extremely powerful thousand-year-old dark spirit, is a primary antagonist of Season 3 which possesses Stiles Stilinski.
Nature & Personality
Kitsune have a reputation as tricksters. They have a naturally deceptive and mischievous nature, depicted as not caring for the concept of right or wrong. They play tricks on people, i.e. committing thievery, subterfuge or seduction. At their best, kitsune can be benevolent, while simultaneously behaving subtly, and malevolent or amoral at worst.
Though mischievous in general, kitsune simply have their own unique sense of ethics and honor. They are natural warriors, having an inherent aptitude for melee combat and weaponry. However, kitsune living in the human world have shown they are capable of consideration, empathy and living peacefully with their human neighbors.
"All the myths about skinwalkers say they're evil."
"They say the same thing about kitsune." - Kira Yukimura and Noshiko Yukimura
Fox Spirit
This spiritual 'fox' bestows a kitsune their trickster and warrior instincts and aptitude, as well as their supernatural abilities. A kitsune's fox spirit can be accessed, brought forward by a kitsune's ability to wield weapons, explained by Ken Yukimura or by their indulging in their elemental abilities. The fox is also affected by a kitsune's Tails in an adverse manner from what's been seen so far. In Thunder kitsune Kira's case, her swordswomanship or affinity for electricity works as a metaphysical gateway to the fox. Her shuriken Tail was once used to subdue the fox during a lethal loss of control.
Latent
When a kitsune is in their younger years, when their powers first manifest, the fox will awaken but will be dormant and is nearly inactive. The spirit is docile and Kira was in complete control of her actions, even when she began to actively learn to and use her abilities. In Season 3, Kira first became aware of her fox spirit when she took flash photos of herself seeing the entity around her. Her kitsune abilities completely awoke after her attack by mass murderer William Barrow. Barrow had attempted to kill Kira by electrocution, unaware it wouldn't even harm a Thunder kitsune and Kira's powers were triggered. Her fox spirit, her aura was later witnessed by Scott using his werewolf vision. He describes the entity around her like an armor around Kira's frame, that it's protecting her from harm.
Possession
In Season 5, Kira was forcibly experimented on by the Dread Doctors. They conducted a lightning bolt to empower Kira, augmenting her Thunder kitsune powers. Her fox spirit was wounded and empowered as a result. Later on, Kira's fox part began to jump out and during times of immense dire, fight-or-flight situations the fox would suddenly and sporadically take control of Kira, possessing her and have her commit actions that were totally out of character for her. Kira would also remember nothing from her blackouts.
Kira's fox was shown to be abrasive and bloodthirsty, and fluent in Japanese, even though Kira knew no Japanese at all. During the fight against the hapless chimera Lucas in 5x04 - Condition Terminal after he was non-lethally subdued, Kira was possessed by her fox then moved to behead Lucas with her sword though Scott stopped her. Later she attempted to kill her mother, Noshiko, during a sparing session, but Ken snapped Kira out of her possessed rage by using her shuriken Tail in 5x07 - Strange Frequencies, showing a kitsune's tails have an effect towards the fox. In 5x17 - A Credible Threat, Kira was possessed once more attacking Scott and Lori Talbot, but Scott pulled her back with his alpha's voice as Kira was an official member of his pack.
Kira's behavior was because of the balance of power had been swayed out of Kira's human hands towards the fox, explained by Noshiko. She also said if the power-hungry fox part of Kira became too powerful it would consume Kira' s humanity and life leaving only the fox. This probable condition implies this was the fate of the Nogitsune as he had no humanity and no original human body, only that of whomever he possessed.
Merged
A kitsune, with proper training, can learn to exert control over their fox spirit and tame them even after they have been previously overcome by the fox. The concerns and priorities of the kitsune become those of the fox's and a kitsune has total control over their actions.
This can be achieved through training with other animal spirits, similar to that of Kira's training with the skinwalkers. Mental health, balance and mental strength can serve to overcome the fox and help a kitsune know their limits. Noshiko attempted to help Kira regain control over her inner fox spirit through acupuncture. Ken also advises Kira that to tame the fox, she should use her mind as a weapon to "outfox the fox."
In 5x20 - Apotheosis, Kira, partially returning from her training from the skinwalkers, had tamed her fox spirit with complete control over her actions and abilities in time to help her friends against the assembled villains and dangers. She was able to use all her talents, her swordswomanship, strength and abilities safely.
Aura & Appearance
Void kitsune in their spirit guise possessing a host, sport, plaque white eyes with chrome fangs, amongst other demonic features afterwards.
Kitsune, in their younger years, naturally possess an aura in the shape of a flaming fox.
Initially this aura is only visible to beings with a supernatural vision, or by use of a developed image using flash photography. They can eventually learn to mask, conceal this aura to hide themselves. In Illuminated, Kira shows Scott her then unidentified aura via a photo. Later on, he locates Kira using his werewolf vision and sees her Fox-shaped aura around her frame in full detail.
In the heat of battle, Kira's aura would become naturally visible. It would flare up all around her, she'd experience losses of control and an innate bloodlust, even coming close to killing her mother. Noshiko explains this is due to the power within Kira being in conflict and out of balance between Kira's human side and the Fox.
In A Novel Approach, Scott witnesses Kira's Evolved aura with his werewolf vision when he and Kira are looking for Kira's belt sword. The Fox Spirit has grown from simply encasing and shielding Kira to flaming all around her, grown in size and had taken on a more threatening shape. It has also become separate from Kira as the Fox points out the location of the misplaced sword to the werewolf with Kira none the wiser.
Like regular supernaturals, kitsune are bound by certain metaphysical rules. Being the tricksters, however, the rules that govern kitsune are rather subtle. These restrictions affect their everyday life and abilities.
Fox spirits & Canine werecreatures
It has been featured in stories and stated several times that foxes and wolves do not get along. This wild relationship is reflected in the kitsune's supernatural repercussions regarding that of a canine werecreature. A kitsune's abilities seemingly have an adverse effect when exposed to a canine shapeshifter.
Stiles Stilinski: You can't be a Fox and a Wolf.
If an alpha were to bite a kitsune, they'd lose their kitsune abilities by changing into a new canine shifter, like a regular human. The bite can also exorcise a nogitsune of its host because the body is changed.
Foxes, in the real world, are solitary animals. They are known to be notoriously pesky and rely on their cunning to survive. In contrast, wolves, coyotes or other pack animals are innately predators, but also social creatures. Wolves are more direct, forthcoming and follow a code of loyalty.
One particular kitsune, a nogitsune who had renounced his humanity, went on a terror spree while operating by his own rules as he saw fit. More than just simply his monstrous nature, he appeared to play by these rules as if they were to come by naturally. When he was first summoned by Noshiko Yukimura, shehad intended for him to possess her to escape death and seek justice for a mass slaughter. However, it's stated that kitsune are not meant to be used or controlled, commanded by a master. This could be because of the rule that foxes are solitary creatures, they operate independently.
In mythology, kitsunes are commonly portrayed as tricksters. They are known to play games and tricks on their victims. In order for a game to be played, it must have rules for the players to operate by. Languages, for instance, don't follow a fully concrete set of rules as they are often complex or interchangeable.
In Season 5, Kira found she is unable to read the coded novel featuring the para-scientists, the Dread Doctors. The novel had been written by Gabriel Valack to work as a tool to trigger the memory senses of the brain to uncover a victim's repressed memories. Mason Hewitt offers Kira input with a theory that fox spirits have difficulty with language. He recounts a myth where people could identify kitsune. When answering a phone call, the receiver would say "Moshi, Moshi" ("hello", in Japanese). They'd say the word for hello twice which would promptly confuse a kitsune because it's a language trick. He surmises Kira can't properly read the novel because the entire coded story is one big language trick and it's confusing the Kira's fox part. Noshiko confirms this theory and instructs Kira how to overcome this issue. The story was what was confusing the fox, so she should read the book but not follow the story; she should read it backwards.
Main articles: Super-Strength, Super-Speed, Healing Factor
Kitsune are known to have enhanced strength and speed. They are able to exert greater strength, run faster, jump higher and react quicker than what should be humanly possible. Using these superhuman traits in tandem, Kitsune can be efficient masters in combat.
Kira discovers her enhanced speed in Letharia Vulpina, outrunning every one of her fellow students during a cross country session. She also discovers her capacity to fight utilizing her strength and reflexes in combat against the Oni later in Season 3. In Smoke and Mirrors, she punched a wall, breaking off a piece of obsidian.
They also have an enhanced healing factor. They are able to heal and repair their cells faster than that of a regular human.
In 1943, Noshiko Yukimura never contracted pneumonia during an outbreak at Oak Creek during WWII. Noshiko was later shot by massive gunfire and was only rendered incapacitated. She was able to heal herself over a matter of days.
In Smoke and Mirrors, Kira activates her healing ability by causing herself pain. She saves herself from a near-fatal chest wound, recovering over a day.
They are able to easily learn how to use weapons or any kind of tool they can get their hands on. They can wield their tool with intuitive proficiency in speed, power and skill. With this superhuman coordination, Kitsune easily become masters in weaponry.
This coordination also supplies the Kitsune's weapon with supernatural properties.
In Season 3, Kira Yukimura, a young Kitsune just coming into her powers, realizes she has a natural aptitude for wielding a katana sword. In Letharia Vulpina, she's able to put up a fight against Oni after touching one for the first time. After a few days of practising with a katana, she's able to twirl, utilize a blade with expert precision and skill, naturally coming into her capacity for swordswomanship.
Kira's mom, Noshiko is a kitsune who's recently sacrificed her Tails, and consequently lost her powers. She still wields natural skill with a blade nonetheless, engaging Kira in a training session in Strange Frequencies.
Kira also wields other particular weapons with similar skill. Using nunchakus, she incapacitates a hunter in The Dark Moon. In Condition Terminal, she throws a shuriken slicing and disabling a burglar alarm. She easily uses a lacrosse mesh stick in Muted.
One known supernatural property of a weapon being wielded by a Kitsune is exorcising of a nogitsune. In 1943, Noshiko Yukimura exorcised a very powerful nogitsune from Rhys' corpse. The power from the exorcism shattered the sword.
In The Divine Move, Kira performed the very same technique on the same nogitsune spirit. Because the nogitsune was already being exorcised from Scott McCall's Bite, the blade remained intact this time round.
Kitsune can wield, use and perform a unique form of magic. This is called FoxFire, their signature talent.
Using FoxFire, Kitsune can conduct rituals, perform functional magic etc, according to their will, and so they are sufficient magic users. The FoxFire of a Kitsune corresponds to what variety of Kitsune he/she is. Foxfire of a single Kitsune can also affect other types.
Kira, being a Thunder Kitsune, wields Thunder FoxFire. She is naturally immune to electricity, she can absorb, dispell and manipulate this form of energy in whatever manner she likes.
In Galvanize, Kira unintentionally absorbed the megawatts of the electricity upon being electrocuted by serial killer William Barrow. The Nogitsune had arranged the whole ordeal so Kira's burst of Thunder FoxFire would supercharge the Nogitsune's power and possession over Stiles' body.
Kira is taught by her mother Noshiko how to utilize her Thunder Foxfire. She shows her how to use a bolt of lightning to reforge her katana in The Fox and the Wolf, and electrocuting Scott physically suppressed his heartrate, sending Scott into a vegetative state in Time of Death.
The FoxFire of a nogitsune, or a kitsune of type Void, is suited to a Nogitsune's hunger and cause for chaos and pain.
A very powerful Dark kitsune wielded a Foxfire that manifested as supernatural house flies, his animal motif. Properties of this Void Foxfire included mind control that could be inflicted upon other beings by the flies physically infiltrating the bodies of such people. Victims of this FoxFire were under the nogitsune's control similar to that of possessing a host, though to a lesser degree.
Because the nogitsune was immortal, had rescinded his humanity and no longer possessed a physical human form, his FoxFire allowed him to realize his very being as a house fly.
Kitsune are capable of realizing and projecting illusions upon others. The villainous nogitsune of Season 3 is the only known kitsune to have exhibited this power. He was able to perform this talent to near-perfect precision.
In Riddled, the nogitsune trapped his host Stiles Stilinski in an illusion within his own subconscious, while the teenager is still asleep. Stiles sees himself in the basement of Eichen House and his left leg is caught in a steel-jawed trap. The void kitsune is able to alter the reality of the illusion while psychologically torturing Stiles. Suddenly the trap is on Stiles' right leg before switching back to his left.
In De-Void, he traps Lydia Martin and Scott McCall in illusions of their past: Lydia was taken back to the night of the school formal (Formality), and Scott was enagaged in a passionate encounter with Allison Argent during the time of Currents. Lydia was snapped out of the illusion by receiving Peter Hale's voice on the banshee frequency, and Scott broke himself free of the manifestation by remembering he and Allison weren't together at the time.
Suddenly, they're present in a reality consisting of a Japanese garden, where it's snowing. The Nogitsune, as his original host incarnation, communicates with them while mystically representing his real-time counterpart, Void Stiles. Scott and Kira are convinced they are fighting off the Oni. Stiles is finally able to deduce the reality is an illusion upon seeing reflections of school property on Kira's katana. Though they feel the pain and exhibit wounds from the Oni's blades, they eventually overpower the Nogitsune, which breaks the illusion.
Upon the reality's dissolution, Scott's Pack eventually appear at where they left off, the school's entrance heading into the building.
Kitsune achieve and collect their Tails as they age, and grow in power and wisdom.
Tails are manifested as physical objects. Due to their enhanced coordination, Kitsune prefer to have the objects representing their Tails altered into weapons they can wield.
Tails are formed when a Kitsune triggers, uses or masters each of their supernatural talents. The more Tails a Kitsune possesses indicates the Kitsune's power level. The older the Tail is, the stronger the weapon shall be.
Kitsune share a synthetic relationship with their forged Tails. Like how the full moon is to werewolves, Tails are also the source of a Kitsune's power.
Noshiko used her Tails in her combat against the Nogitsune. She sacrificed her Tails to call forth the Oni from the Nemeton, and command the demons. Eight of her Tails were sacrificed to manifest the demons. The older the kaiken sacrificed, the stronger the respective Oni became. Noshiko's ninth Tail, her first and oldest, was stolen from her by the Nogitsune in De-Void. The Dark kitsune used the kaiken to enhance his FoxFire to perform mind control over the town's local werewolves Isaac Lahey, the twins and Derek Hale. In Insatiable, the Nogitsune sacrificed Noshiko's final Tail. He carried this out with the Oni Noshiko had previously summoned so close to him. This resulted in the control of the Oni being exchanged from Noshiko to him.
Because all of Noshiko's Tails have been sacrificed, her power is severely depleted so that she's now only "technically" a kitsune.
In Strange Frequencies, Ken slams and embeds Kira's shuriken into his desk. This action snaps Kira out of a Kitsune homicidal episode.
Real World mythology of the kitsune
In mythology, Kitsune are actually described as being natural born foxes who are immortal, but once they are a 100 years old, they can shapeshift into human form. They are known to assume different human forms, most commonly that of an attractive woman to seduce men. They are known to trick people, to play elaborate games with intentions that can vary from benevolent (Foxes known as Zenko) to malevolence, or even maliciousness (Yako).
Kitsune are said to grow up to nine tails.