Artist.

Artist name: 秋月 からす
(Artist gives reading as either "Shuugetsu Karasu" or "Akitsuki Karasu" on the Pixiv commentary of post #642878. You can call him either way)

See also

• Pixiv account: http://www.pixiv.net/member.php?id=74327
• Nico Nico Seiga images: http://seiga.nicovideo.jp/user/illust/2336957
• Twitter account: http://twitter.com/karasu_s
• Twitpic account: http://twitpic.com/photos/karasu_s