Green Mask has sand green skin and short yellowish-white horns. He has human-like ears, and a wide human-like nose. His eyes are also partly human-like but are much bigger and have blue irises. His teeth are not all the same size, with one of them even sticking out from his mouth. He wears a dark grey cloak which also has a gold pattern. He wears gloves that are white and boots that are brown. Under the cloak, his shirt is black and has a red belt around it. In the 2008 Go! Godman film, he wears a ruff around his neck, and his cloak is lined with red fabric. Overall, Green Mask appears to resemble a European Demon or Gargoyle.
Green Mask was the twenty-third monster to battle Godman.