Noh mask representing the red avenging demon, HANNYA, 25 cm

Hannya (般若 の 面) is, in the fantastic legends of Japan, the ghost of a woman returned to earth to quench her revenge. The term "Hannya" comes from the Sanskrit "prajna" which means "great wisdom".
Hannya demons are very present in the Noh theater where hannya masks are found in the plays Aoi no Ue and Dojo-ji. In Aoi no Ue, the jealous Rokujô is overcome by the recitation of the sutra of Hannya which was recommended to exorcise the women-demons.