Hannya is a mask used in Japanese Noh theater that represents a woman turned into a demon by jealousy and obsession. It gives form to a female onryō — a vengeful spirit carrying resentment toward the living — and is recognizable by its two sharp bull-like horns, metallic eyes, and a wide, leering mouth.
In Noh it appears in plays such as Aoi no Ue, Dōjōji, Kurozuka, and Momijigari. The mask’s color signals the character’s rank: a white hannya for refined figures like Lady Rokujō in Aoi no Ue, a red one for lower-born characters like the peasant girl in Dōjōji, and the darkest red for true demons. Its grades also track the depth of transformation, from namanari (生成), a woman on the verge of becoming a demoness, to chūnari (中成), the hannya itself, and finally shinja (真蛇), also called honnari (本成), the most intense, snake-like form.
The face shifts with the angle from which it is seen. Looking straight ahead, the mask is frightening and full of wrath; tilted slightly down, it turns sorrowful, as if weeping. This coexistence of rage and grief in a single face is what makes it an emblem of jealousy and resentment. By one account the mask takes its name from Hannya-bō (般若坊), a monk of the Bunmei era (1469–1487) said to have perfected it, while another links the word to the Sanskrit prajñā (wisdom); the true origin remains debated.