A Nogitsune is a Dark kitsune, one of type Void. They draw their power from strife, chaos, tragedy and pain; they feed off of pain.
Nogitsune are particularly prideful, they have a dark sense of humor and are dangerous when they have been offended.
Once a nogitsune spirit possesses a human host, the victim will manifest multiple chromed fangs, a white-gray palor as well as white blank eyes.
Two Nogitsune appear during Season 3 of Teen Wolf.
The other was encountered by Chris Argent 24 years prior to the series timeline who'd possessed a kumichō, the boss of a Yakuza family.
Kitsunetsuki is a Nogitsune's ability to specifically possess and control others to carry out the dark spirit's bidding. It literally translates to "possession by a Fox spirit." Another aspect of kitsunetsuki is to copy and assume the shape of its host (a form of shapeshifting).
If a Fox Spirit is able to possess a human host, and take on their human shape, this means the Fox is over a 100 years old.
On Teen Wolf, "You can't be a Fox and a Wolf." Due to this, werewolves or Wolf-based creatures/spirits are immune to Kitsunetsuki.
The control of a Nogitsune spirit can be countered by the herb letharia vulpina. Poisoning by the herb will break the Nogitsune hold over said host temporarily. Nogitsune spirits can be completely exorcised from their host, or their host-copy shapes can be killed, by two known methods. One is changing the body of the host. Such as being changed by the the Bite of an Alpha werewolf because of said rule above. The other method is being slain by a weapon wielded by a Kitsune.
Under the Nogitsune's possession, he rose to the status of kumichō, or boss, in the family, according to Katashi.
Chris Argent conducted his first gun deal with the Yakuza gang at the age of eighteen 24 years prior to the series. When the sun set, three Oni appeared in the middle of the deal. After cutting down the Yakuza entourage, the demons impaled the Nogitsune upon their swords, killing the Dark Kitsune.