The generic term for the Inari, Kudagitsune, and Osaki classes of spirit foxes. Represented by the nine tailed fox, many have very strong supernatural energy. Also, when they beat their tails together, they create something known as "kitsunebi" (fox fire) and completely burn any human who does them harm.
As befitting their name, the Yōko fit the general shape of their animal counterpart, the fox. However, a Yōko is a Human-sized or larger creature, possesses multiple tails, and despite its fox-like form, is actually a humanoid creature, with appropriately present hands, though they can also be on all fours if they choose to. Another signature feature is that they sometimes possess a number of elaborate, tattoo-like markings on their bodies, concentrated on the shoulders up to the head, though this is likely dependent on factors such as the type, power level, age, etc.
One unique aspect of this species is that their appearance changes over time, which is directly correlated to the number of tails that he or she may have, which is in turn tied to factors such as time, inherent talent, training, etc. and the overall gaining of wisdom during ones lifespan. These factors in turn will increase the number of tails that a Yōko will possess; the more tails, the stronger and wiser the Yōko will be. Yōko can have as many as nine tails, hence the representative for all classes of Spirit Foxes is the nine-tailed fox, the pinnacle of this species. At that point, they are at their highest stage of power, which is potent enough for them be worshiped and renowned as gods by humans and monsters alike, which is when they are firmly placed in the S-class category of monsters.
regardless of their age or class, a Yōko is able to take on a specialized, enhanced form which maximizes and condenses the total amount of power that the fox has relative to the number tails he or she may have. This form is known as the "Battle Form." In contrast to the base-line or human form, this form combines aspects of both, albeit oriented for the needs of combat and the overall purposes of intimidation. This form has a streamlined, muscular upper torso, which matches their human form, albeit with the iconic fox ears, while the lower torso is that of their standard form, which is now placed for optimum, bipedal movement.
The fiery manifestation of their yōki is their primary weapon, which covers their bodies and is generated either in their hands or most notably, when they lash their tails together. This burning energy is extremely hot, and possesses the potential to burn almost any enemy to ashes.