Yamachichi are one of two forms an extremely long-lived Nobusuma may become in ancient Japanese folklore, and while originally the spirit of an ancient bat, the Yamachichi has since changed into an ape-like creature with a pointed snout and sucking lips. Often confused with the Satori, these creatures are not related, despite sharing similar appearances.
Yamachichi have retained the vampiric qualities of the Nobusuma, but taken it to an even darker element, as they become nocturnal harvesters of human life-force, sneaking into the homes of sleeping humans and using their sucking lips to drain the life out of their victim. The yokai would then wake a victim after a nightly feeding via a prod to the chest, then flee into the night without being seen. It was said those awoken in such a manner would inevitably die within a day.
While dangerous, the Yamachichi could be defeated if a relative or victim awoke and caught the yokai in the act of draining their energy. The creature would panic and flee, extending its would-be victim's lifespan significantly in the process.