Lambdadelta is a powerful witch in the series 'Umineko no Naku Koro ni.' Known as the Witch of Certainty, she holds authority over events that are guaranteed to happen, no matter what. Lambdadelta is playful yet extremely dangerous, often acting with a childlike demeanor but possessing immense magical power. She is a key figure in the witches' game, serving as both an observer and participant in the battles of logic and mystery, and has a complex relationship with other witches, especially Bernkastel.