Doujinshi circle. Crimson is also the name of the main artist herself. The illustrator of Aoi Sekai no Chuushin de.
Her works are well-known for distinctive meme-ish phrases.
For example: "くやしい...! でも...感じちゃう...!" or "ピクンピクン".
Pen-name: クリムゾン (Crimson)
Circle name: クリムゾン (Crimson) or クリムゾンコミックス (Crimson Comics)
Old circle partner: カーマイン (Carmine)
http://dic.pixiv.net/a/クリムゾン
https://www.pixiv.net/users/772642
https://www.pixiv.net/stacc/crimson23
https://twitter.com/crimson_3
https://twitter.com/intent/user?user_id=147626187
http://dic.nicovideo.jp/id/562815
https://sketch.pixiv.net/@crimson23
https://www.youtube.com/@Official-cq3tr
http://p.twipple.jp/user/crimson_3
