shiina_lemon
Creator of Shiina Isana and Shiina Rei. Usually he uses his pixiv account for browsing other artists' works.
Pixiv nickname: 椎名 檸檬 (Shiina Lemon)
The other names: 遊楽狐 (Yuurako), りゅーきち (Ryuukichi) or 檸檬竜飴
See also
* Pixiv account: http://www.pixiv.net/member.php?id=1433565
* Niconico account (unconfirmed): http://www.nicovideo.jp/user/1613723
* Twitter account: http://twitter.com/ryukiticn