The position of Game Master (ゲームマスター,Gēmumasutā) gives one the ability to craft a tale using a game board. According to other witches, there are several gameboards that exist, however in this case the title of Game Master is held by a Witch or Sorcerer and the gameboard in question Rokkenjima from October 4 to October 5, 1986.
When creating a tale, the Game Master must always avoid creating a Logic Error or the game will instantly be destroyed.
It is mentioned in Dawn of the Golden Witch that Bernkastel was trapped in a game with an unknown Game Master before becoming the Witch of Miracles. The manga despicts this scene with silhouettes that resemble Rika Furude and Hanyuu from Higurashi When They Cry.