According to Japanese belief, the shōkera is a very large, dark-skinned, three-toed demon which spends most of its time lurking about on rooftops. Not much is known about this fearsome beast aside from its hunting practices, though it is believed to be some kind of demon with connections to Kōshin, an esoteric Japanese folk religion with origins in Taoism.

Shōkera only appear on Kōshin-machi, a special night in the Kōshin faith which occurs every sixty nights. A shōkera spies through windows, doorways, or skylights in houses, watching for the inhabitants to do wrong or impious things, after which it pounces down in a vicious attack. Because Kōshin is no longer a very widespread religion, and because victims of shōkera attacks would only be implicating themselves as wicked by admitting to seeing one, little else is known about the shōkera’s specific mannerisms.

According to Kōshin, there are three spiritual worms or insects, called the sanshi, which live inside every human body. Every sixty nights, on a special night called Kōshin-machi, these worms leave the body while their host human sleeps. The sanshi travel to Heaven to report on the good and bad deeds of their human. The emperor of Heaven then uses this information to lengthen or shorten people’s lives according to their deeds. While good people have nothing to fear from Kōshin-machi, the wicked might try to circumvent having their bad deeds reported by staying awake and reciting prayers all night long during these special nights so that the sanshi cannot leave the body. The shōkera lurks about on rooftops during these nights, peering into windows and hunting for anyone violating the laws of heaven in this way.