Kōshin

Kōshin (庚申) or Kōshin-shinkō (庚申信仰) is a folk belief in Japan with Taoist origins, influenced by Shinto, Buddhism and other local beliefs.

An event related to the belief is called Kōshin-kō (庚申講), held on the Kōshin days that occur every 60 days in accordance with the Chinese sexagenary cycle. On this day some believers stay awake to prevent Sanshi (三尸), entities believed to live inside the bodies of believers, from leaving during that night in order to report the deeds of believers to the god Tentei.

It is not known when this belief arrived in Japan, but it was widespread among the nobles of the imperial court by some time in the 9th century. The Japanese monk Ennin, visiting Tang China in 838, wrote that "This night no one sleeps. It is the same as New Year's Eve and the nights of Kōshin in our country." In the Muromachi period, Buddhist monks started to write about Kōshin and spread the belief to a wider public. Numerous monuments or pillars called Kōshin-tō (庚申塔) (or also Kōshin-zuka (庚申塚)) were erected all over the country, and the belief remained very popular during the Edo period. However, after the Meiji government issued the Shinto and Buddhism Separation Order in 1872, Kōshin and other folk beliefs were officially rejected as superstitions.

Belief in Kōshin survives, although it is far less popular than it once was. Many Kōshin-tō have been moved inside Buddhist temples or private homes, but many remain alongside roads and there are still some well-maintained Kōshin-dō (庚申堂) (Kōshin halls) either attached to Buddhist temples or standing alone.