literally: bone woman is a yōkai depicted in the Konjaku Gazu Zoku Hyakki (1779) by Toriyama Sekien. As its name implies, it depicts this yōkai as a woman in the form of bones.
According to Tōhoku Kaidan no Tabi by Norio Yamada, there is an odd tale in the Aomori Prefecture about a yōkai under the title of "hone-onna". It says that in the Ansei period, a woman who was said to be ugly by those around her became a good-looking skeleton after death, and walked around town as a skeleton to let everyone see. It is said that she likes fish bones and would collapse upon encountering a high priest.
