The spirit guardian who lives in the darkness of the Beast Spear.

Spoiler

She is the sister of Giryō, who sacrificed her life to create the blade of the spear. She reincarnated as Yuki, the first of the lineage of powerful lady shamans, all but one has the same look as her. Jie Mei is able freely materialize anywhere needed, and first appeared to help prevent Ushio from transforming into a Beast by having his soul totally absorbed by the spear.