I'm looking through my manga. It looks very much 
like a woman in it, whose name I don't know. ^_^ 
The necklace is the same; the eye-markings are 
the same; and she wears dangly earrings. The 
headdress and clothes are different, but this 
particular character goes through at least two or 
three wardrobe changes in the volume I'm looking 
at (v.8). Since Yakumo Tatsu has only 2 eps, it's 
very likely (if it's the same person), that she 
had other costumes in the earlier manga volumes 
corresponding to what got animated.

Her artbook self (if it's the same person) has 
red eye-markings, rather than purple. So, hrm, if 
anyone else can confirm/deny the speculation, 
that would be great. Until then, you can pretend 
that she belongs to Yakumo Tatsu/Eight Clouds. ;o)

-Cres