Mikura are transformed Youkai created by Ekou Hoshunin. Eko uses them as pawns although they seem to either not realize or care. They disguise themselves as humans but have a lust for blood and must consume it to continue living. Nue is a rogue among them.
Mikura can appear as humans but eventually have to succumb to their demon forms and consume human blood. Their human appearances differ to whatever they like but their demon forms are usually constructed around the powers they have. Their demon mode usually appears as if their whole bodies are mechanic, but with a few amounts of flesh shown around certain parts of their body.
The Mikura were created by Eko for his own evil intentions. Eko is seen meeting with his higher-up Mikura who usually refer to him as Lord Eko. All of his higher-up Mikura are killed and Tsuchigumo is sacrificed. She accepts to being a sacrifice for Eko's purposes, though with a painful scream as she is squashed to death by the tentacles formed from the Nue brothers.