Yamabiko

Yamabiko is one of Zeref's creations and he has long forgotten his true purpose. For many years he has remained in the shadows while allying himself with no one. That changed when he saw Itsuki in his demon form and became one of the first members of the Hyakki Yagyō.

Etherious Physiology

 * Supersonic Speed:
 * Sound Manipulation:
 * Sound Aura: Yamabiko's power over sound is so great that he is constantly being protected by a thin layer of vibrating air, otherwise known as shockwaves. The layer is able to protect Yamabiko from very powerful attacks, but it will always lose against a barrage of attacks and very precise strikes because of how it is filled with tiny weak points. Its greatest weakness is the fact that his feels are what determines what the shockwaves try to protect him from and what they will let pass through. This means that controlling Yamabiko's emotions is all that it takes to get past this layer of defense.
 * Etherious Form: