Artist.
Japanese name: ็ฆ่ธ (ใ ใใฟใฑ, Mutsutake)
Old name: ็กๆ (Mugetsuki)
Circle & site name: ๆจๅบ (pronounced as Onshou, spelled as ON-SHOW) (Circle partner: Ishibashi Shingo)
This artist seems to be Mutsutake's Cookie_(Touhou)-themed account.