Miboshi

Name:Miboshi(箕宿)
Real Name:Unknown
Also Known As: Mimadou

Age: Unknown
Family: Unknown
Place of Birth: Unknown

Power: The parasitic ability to possess other bodies, as well as spiritual powers much like a sorcerer of Chichiri's ilk.

Seiyuu (Japanese):
Voice Artist (English):


 

Background: 
Miboshi is essentially dead - at least his spirit inhabits the unfortunate body of a shrine priest he chose to invade...and that's about all that's known except he's a parasite who shifts from body to body.
Miboshi appears extensively as the villain of the piece in Tamahome's Gaiden ShugyokuDen (under the name of Mimadou, where he uses serpents to do unseemly things to young women and also uses his power of possession to create all kinds of problems for Tama and his young village friends). Though written after the anime, I get the feeling this was done mostly because Miboshi had so little of a role in the manga - and it was a chance to give him more of an airing.
Despite this there is still no clue given to his background and his name is still wrapped in mystery.

Character:

We don't get to see enough of Miboshi to really know this. He appears, he gets killed by Tatara, he possesses Chiriko, he gets killed by Chiriko - exit Miboshi about two episodes after he entered. He's kind of cruel in the sense that he seeks vulnerable bodies to infiltrate and use for his own ends. He's definitely a sorcerer, and creates monsters in the same way that Tomo creates illusions. He takes over Chiriko's body and is only destroyed by Chiriko's will and determination to die and take Miboshi down with him. He's also good with potions, since in the manga he is credited with being the one who created the kodoku (diedu) substance used to poison Tamahome. He also captures Miaka's voice to prevent her speaking to Yui. In short, then, he's a pretty all round unpleasant guy. And he's probably been around for some time.