I'd appreciate it if someone could help me find a name for the artist for this picture. The pixiv page is http://www.pixiv.net/member.php?id=25085 but baku and baku_(artist) are already in use and the homepage http://witches.jp/p4/index.html doesn't seem to have the artist name anywhere (that I can find, as I can't read Japanese).

Well it seems the artist's account name (as opposed to the artist name he chooses to display) is "bac", as you can see in the url:
http://img03.pixiv.net/img/bac/1398501_m.jpg

So how about using that?

I'll do that. Thanks.