Artist.
Artist name: "Robert Knight" or "Knight"
Site names & pixiv nicknames: "knighthead (騎士)" or "Error"
Has the signature E☆K
https://www.pixiv.net/users/2257734
https://www.pixiv.net/users/15376185
https://www.pixiv.net/stacc/DreamError
https://www.pixiv.net/stacc/eroknight
https://twitter.com/MangaArtKnight
https://twitter.com/intent/user?user_id=76740870
https://www.deviantart.com/knighthead
https://pawoo.net/@eroknight
https://pawoo.net/web/accounts/329074
https://sketch.pixiv.net/@eroknight
https://dreamerror.tumblr.com
https://www.youtube.com/user/MangaArtKnight
http://dreamerror.blogspot.com
http://plus.google.com/109876731103459840670/posts
https://piczel.tv/watch/eroknight
https://twitter.com/OshiriKami
https://twitter.com/intent/user?user_id=760705559196790784
https://www.facebook.com/RobertKnightArt