Noh is the classical theatre of Japan which was codified in the 14th century under the father and son actors Kan'ami and Zeami under the patronage of the Shogun (supreme military leader) Ashikaga Yoshimitsu. The performances utilise masks and elaborate costume.

The mask represents a female serpent-demon filled with malicious jealousy and hatred. Two sharp horns sprout from the temples and bulbous, metallic eyes lie half hidden beneath scowling brows. The gaping mouth is full of gold teeth, with upper and lower fangs that heighten her ferocity. The flesh tone of the face varies depending on the social rank of the woman portrayed, with a lighter complexion indicating aristocratic status. The mask is worn by the protagonist (shite) in the second acts of Aoi no Ue, Dojoji, Kurozaka and Momijigari. The first two plays depict women betrayed or spurned by their lovers; the second two portray demons who first appear in human form to trap the unwary. Several traditions account for the name Hannya: the most plausible account traces the origins of the mask to the mask carver Hannyabo who was active in the late 15thC or early 16thC.

The mask is carved from a single piece of hinoki with the horns added as separate pieces and fitted into sockets on the upper part of the forehead. There is a substantial layer of gofun over which the details have been added. The carving is extremely well executed and the transformation from human to demon is well represented by the artist. The overall carving creates sharply defined features, particularly to the brows, nose and lips.

The deeply sunken eyes, inset with a gilded metal plate which is skilfully fitted into the eye sockets, stare out from under malevolent brows. The sharp nose juts out of the face and the horror of the demon is emphasized by the bright red lips of the drawn back mouth which reveal the inhuman teeth and fangs. The teeth are also of gilded metal, excellently fitted, with highlights in sumi. The curving horns are rather straight and pointed; blunter and deeper curved horns are more usual for Hannya.

The surface of the mask is painted white with delicate details in pale pink emphasising the creases on the face. The hair is finely drawn in sumi and also helps indicate the transformation from human to demon. The top of the head is painted with the parting and fine hair typically found on a mask of a beautiful woman, but many fine strands of dishevelled hair are drawn around the forehead. The strands of fine hair (associated with the mask of a young woman) double back in to the parting to join up with the main area of hair but stop abruptly in the middle of the forehead. Throbbing veins are also visible on the forehead, indicating the wrath and anger of Hannya. The protuberant ears and jutting chin demonstrate further how far removed from humanity the once human character has now come. The depiction of the transformation from a beautiful woman to the demonic Hannya has been perfectly executed by the skills of the carver.

The interior of the mask is plain wood with a dark stain through which the fine chisel marks are visible. The ends of the horns are visible where they are socketed into the main body of the mask. There is significant wear to the cord-holes with lines of wear where the original cords have rubbed away some of the paint, gofun and wood.