Yōki

is the energy and power utilized by yōkai; a demon's yōki acts as the source of their power. Demons have been shown to manifest their yōki in the form of energy attacks, channeling it through their bodies to increase their physical aspects, such as Inuyasha channeling his into his claws, or their weapons, such as Inuyasha and Sesshōmaru channeling their yōki into their sword to unleash powerful attacks, and by releasing it in the form of their jaki for varying effects. The energy can also take the form of certain elements such as fire and lightning. A demon's yōki also becomes stronger the more they commit evil deeds, and or being born from two pairs of demon's with considerable power such as daiyōkai.

Yōki is also known to be very dangerous, able to corrupt or outright destroy weaker beings.

Known Effects

 * Physical Augmentation: Demons are able to use their yōki to greatly increase their physical prowess. An example this includes Inuyasha's Sankon Tessō to increase the strength and attack range of his claws.
 * Constructs: In some cases yōki can be used to create certain constructs. Examples of this include Inuyasha's Hijin Kessō, Sesshōmaru's Light Whip, and Naraku's barrier.
 * Elements: A yōkai’s yōki can be channeled into the form of various elements. An example includes Sesshōmaru being able to channel his yōki into lightning through his Tōkijin to unleash in the form of lightning blasts. In some cases for those already possessing elemental abilities, their yōki can be used to make them more potent, much like how Naraku is able to channel his jaki through his miasma.
 * : An ability mostly possessed by yōkai swords. When yōki is channeled into the sword, the user can strike their enemies without the blade making physical contact. This is a starting ability for yōkai swordsmen, used to defeat weaker enemies until they develop more of their power. Although not as strong as a full powered attack, the kenatsu is still very effective. One swing can damage or even kill weak yōkai with the slightest bit of pressure, and cause major damage to the surrounding area. Figures such as Sesshōmaru can channel their elemental power into the blade for elemental damage.
 * Slashes: The most common form of Kenatsu in which users of yōkai swords project the yōki in the form of slashes.
 * Needles: This was a special case for Sesshōmaru when he wielded Tōkijin. He was able to project powerful energy needless when he needed to dispose of lesser yōkai.
 * Yōki Wave: When users become proficient enough with Kenatsu they can unleash it in the form of devastating waves of yōki, such as the Kaze no Kizu, to slay numerous yōkai.


 * Ōgi: When a yōkai channels their yōki its maximum, they can unleash in the form of powerful ultimate attacks such as the Bakuryūha or Sōryūha to slay countless yōkai and powerful enemies.


 * : The visual manifestation of demonic energy in the form of a whirlpool that appears behind a yōkai and is visible to just a few. This vortex can be cut and its effect is an instant-kill upon the demon whose yōketsu is being cut; Inuyasha's Dragon-scaled Tessaiga had this ability.

Relationship with Reiryoku
Naturally given the nature of being using to purify or outright eradicated a yōkai's demonic power, the two are opposite in nature and tend to clash. The connection between Reiryoku and Yōki is interesting as given that there have been instance in which some yōkai have used Reiyoku to strengthen their own power. Examples such as Miko fūji and Oni's head are capable of absorbing spiritual power from monks and priestesses alike to fuel their own power. Another example, although non-cannon, is explained in the forth movie. The guardian miko of Hōraijima, a place where demons and humans lived in harmony, tells Inuyasha that a hanyō is born with both Reiryoku and Yōki, and the two powers merge. Likewise in the film series, Inuyasha often uses the Bakuryūha in conjunction with Kagmome's sacred arrow to both weaken and destroy powerful Daiyōkai.

Know Users

 * Daiyōkai
 * Yōkai
 * Hanyō

Trivia

 * Yōki is also referred to as Yōryoku (妖力, ようりょく (lit. "demonic power, energy and/or strength"), i.e. in Chapter 477.
 * The term, Kenatsu, wasn't used in the original manga until Chapter 162. It's been described as a made-up or very rare term.

Yōki 妖氣