"Takiyasha the Witch and the Skeleton Spectre"
Ukiyo-e woodblock print by Japanese artist Utagawa Kuniyoshi (1798–1861)
Victims of famine who die without receiving proper funerary rites are at risk of becoming gashadokuro. Unable to pass on, these souls are reborn as hungry ghosts. When the bones of hundreds of these victims gather together (due to a village famine or soldiers who die in battle) they can form the skeletal monster. Too large and powerful to be killed, it will continue to feed until the energy and malice stored within the creature has completely burned out. The gashadokuro are indestructible, though Shinto charms can ward them off.
The earliest record of a gashadokuro goes back over a thousand years ago. A samurai named Taira no Masakado led a bloody rebellion against the central government of Kyoto during the the Heian period. His daughter, Takiyasha-hime, was a famous sorceress. When Masakado was killed in battle, his daughter continued his cause. Using her black magic, she summoned a giant skeleton to attack the city of Kyoto. Her monster is depicted in a famous print by Utagawa Kuniyoshi (shown above).