Yōki

Yoki is the energy used by some characters in the Inuyasha universe. More particularily it seems to be the demonic energy used by powerfull yokai or hanyo to perform their attacks. Visually it maniphests in the form of wind vortex around the characters that are visible to just a few. By releasing their yoki energy some characters like Inuyasha or Sesshomaru can slay hundreds of enemies with one swing of their swords