A mysterious witch who appears to Battler following the first game, providing advice and telling him she will support him in his endeavors to solve the mystery of the witch Beatrice. Although an ally to Battler, Bernkastel has a twisted personality and refers to herself as the "cruelest witch in the world", and is only interested in Beatrice's game as a chance to escape her own boredom. She is known as the Witch of Miracles, and she has the power to reset any situation and realize a goal, eventually securing victory even with a 0.0000000000001% probability, so long as it is not zero. Initially stoic, cold, and calm, she slowly reveals herself to be just as impish and cruel as her rival, Lambdadelta.

Spoiler

Bernkastel's true identity is strongly implied to be that of Rika Furude's witch self, formed from the suffering she underwent as she died again and again within the loops of Higurashi. She appears briefly in Higurashi, first to provide advice to the reader during Minagoroshi-hen, and then travelling to the past to create a 'perfect' world where Miyoko's parents never died, preventing all the sins that lead to the gameboard of Higurashi. The relationship between her and Rika is examined more thoroughly during Saikoroshi-hen, where a drunken Rika questions her own humanity and christens herself "Frederica Bernkastel", a slurring of her name with the brand of her wine tacked on. After suffering and giving into her aloof personality as Bernkastel, Rika decides to let go and stop being the witch Bernkastel, though she wonders if perhaps this aspect of herself remains on a higher plane, toying with the fate of lower beings.