Sansei are mountain-dwelling yokai that resemble small humanoid spirits with a single limb, often bent backwards, they are known as masters of the animals of the mountains and exist in a diet of frogs and crabs, which they love to broil in salt.
Sansei are frightening creatures but not often aggressive, sometimes a Sansei will attack a human regardless and when this happens one must shout "Hiderigami!" which will frighten the creature away, if one yells "Sansei!" it will instead cause the creature to curse one with bad luck or even set fire to one's home.