Artist, (former) doujin creator.

Japanese name: 乃藤 悟志 (Naitou Satoshi, usually styled as "Knight O Satoshi" or "Knight ∅ Satoshi")
Circle name: ウェブ乃藤 (WEB KNiGHT ∅)
Doesn't seem to use these names or make doujin anymore

Currently goes under the name kirihalla:

• Twitter account: https://twitter.com/CheapAction2d
• Pixiv account: https://www.pixiv.net/member.php?id=218983
• Pixiv Sketch: https://sketch.pixiv.net/@chepaction2d
• Nijie account: https://nijie.info/members.php?id=2481
• Pawoo account: https://pawoo.net/@chepaction2d

Previous works by him can still be browsed here:

• Digital distribution site: DLSite.com(JP)
• The Doujinshi & Manga Lexicon: https://www.doujinshi.org/browse/author/4042/