Artist.
Artist name: マッハダイ (pronounced "Mach-Dai")
(He always spells his name as "Mahcdai" and says "Wrong spelling? No, it's a feature.")
https://www.pixiv.net/users/2195061
https://www.pixiv.net/stacc/mahcdai
https://twitter.com/mahcdai
https://twitter.com/intent/user?user_id=391363140
https://seiga.nicovideo.jp/user/illust/14748864
https://www.nicovideo.jp/user/14748864
https://nijie.info/members.php?id=1113566
https://pawoo.net/@machdai
https://pawoo.net/web/accounts/571663
https://sketch.pixiv.net/@mahcdai
https://odaibako.net/u/mahcdai