Mama

Mama(ママ, Mama, Mana in the english anime) is the guardian ghost of Opacho

About
Mama is the guardian spirit of Opacho. Although her true form is not seen in the series, its believed to take the form of a sheep.

O.S. "Ram"
O.S. Ram

Description: Using her hair, Opacho creates an Oversoul in the shape of a sheep around her body. The Over Soul have a great offensive power as a single hit from it was able to shatter all of the bones in Umemiya Ryunosuke body.
 * Shaman: Opacho
 * O.S. Type: Spirit Type
 * Spirit Ally(s): Mama
 * Medium: Opacho's hair

Anime/Manga Diffeence
Mama appears once in the anime, as Opacho uses O.S. to help Asakura Hao find the Great Spirit

Trivia

 * In the video game Shaman King: Master of Spirits 2, Mama makes an appearance as an enemy in one of the stages leading to the final boss,