Yonaki babā

Yonaki babā (Japanese: 夜泣き婆 or よなきばばあ, meaning "weeping hag") is a yokai in the form of a crying old woman. She remains outside of the house, weeping loudly all night long. Although it appears that yonaki babā are sharing in the sadness of others, it is sometimes said that they actually weep out of scorn, mocking those who are truly sad.

Myths & Legends
Yonaki babā’s weeping is contagious; those who hear her cannot help but to weep as well. She may return to the same house over and over for many nights to feed off of their sadness. Families which are visited by a yonaki babā night after night invariably fall into ruin.

Yonaki babā’s behavior is similar to that of a class of spirits called  yakubyō gami —minor deities and spirits which bring sickness and disaster wherever they go. Before modern medicine, plagues and natural disasters were often thought to be the works of these spirits. Because repeated yonaki babā appearances are often precursors to the ruin of an entire family, it has been suggested that she may be a kind of yakubyō gami.

Conversely, it has also been suggested the yonaki babā’s arrival may be a divine signal that disaster is near. Rather than bringing disease and ruin herself, yonaki babā may be a kind of divine herald with the duty of warning humans that misfortune, sickness, and death are on the way.

Appearance
Yonaki babā looks like an old woman with scraggly, unkempt hair and plain robes. She appears outside of houses where tragedy has struck, attracted by the sadness of those within.