사공 Sagong, known online as 40.tatt, is a tattoo artist based in Amsterdam, Netherlands, with studio work also taking place in Katwijk aan den Rijn. He specializes in black and gray tattoos as well as micro-realism, creating detailed pieces such as portraits, animal imagery, and symbolic designs. His portfolio features work on various body parts including inner arms, forearms, and legs.

Working out of Ink District Amsterdam, 사공 Sagong combines technical skill with a refined aesthetic to deliver precise and meaningful tattoos. His work reflects a thoughtful approach to both traditional and contemporary styles within his chosen focus areas.