nagatsuki_towa
Artist. Formerly tagged as eien.
Japanese name: 長月 永遠 (Nagatsuki Towa)
Circle name: スタジオカルテット (Studio Quartet)
See also
* Pixiv account: http://www.pixiv.net/member.php?id=254200
* Twitter account (unconfirmed): http://twitter.com/nagatsuki_towa
* The Doujinshi & Manga Lexicon: http://www.doujinshi.org/browse/circle/22828/