kōshin-machi; all-night vigil on the eve of Kōshin day
A historical Buddhist practice of staying awake all night on the eve of the 57th day of the sexagenary cycle to prevent the three worms (三尸) from reporting one's sins to the gods. Originated among Heian nobility and became widespread in the Edo period.
See also: 三尸
Kōshin-machi is a custom that began among the nobility of the Heian period.
During the Edo period, kōshin-machi spread among the common people as well.