Cels Forum

Wrong on both accounts. ^v^  The cel is of a male angel (of course,
he's an "evil angel").  His name is Kouryu.  This cel is of his night 
form.  During the day, he's a little chibi angel and so cute!

I've only seen the manga for this series (it is Wish by Clamp), but
I heard about an OAV series or something in the works.  Maybe it was
finally released. Otherwise, the cel could very possibly be from the 
opening (since I've since that from clips on the web).

Hope that helps!