Zenihebi.

Zenihebi (銭蛇, ぜにへび) is usually imagined as a very small snake the color of old copper coins. Rather than standing out with monstrous size or violence, it is notable for being easily overlooked: a brief glint in lamplight, a narrow body slipping along a beam, or a coil hidden among chests, rice sacks, and ledgers. That restraint is part of its character. It belongs to the close interior world of the kura, not to wild mountains or haunted roads.

Reference works describe it as having a metallic or money-like sheen, a visual sign that the creature is tied to stored cash and long-guarded household savings. The image is intimate and domestic, which makes it different from larger serpent monsters in Japanese lore. Zenihebi feels less like a beast to be fought than like the house's own fortune made visible for an instant.

Zenihebi is remembered as an omen of prosperity. To glimpse one in a storehouse means that wealth has remained in the family long enough to acquire spiritual presence. It does not usually attack or threaten. Instead, the danger lies in how humans respond to it. Folklore warns that anyone who strikes, traps, or kills the snake drives luck out of the household and turns abundance into sudden loss.

That pattern places the zenihebi among cautionary beings of domestic economy. A careful household leaves it alone, keeps the storehouse in order, and treats the sighting as confirmation that savings have been properly guarded. The creature therefore mediates between material thrift and supernatural consequence, giving a moral edge to the management of wealth.