Samdugumi is a creature from Jeju Island’s shamanic narrative (bonpuri), a grave-fox with three heads and nine tails. It disguises itself as a human to prey on a family, and is said to be vulnerable to cast iron and raw eggs.
It is an independent Jeju variation of the fox-shapeshifter tales of the Gumiho lineage. Because it has fixed weaknesses, it shows the structure of Korean creature-defeating lore, in which one confronts the monster by reasoning out its rules and taboos.
The frame of the tale is a son-in-law who takes three daughters in turn. Samdugumi comes in human shape, receives a daughter in marriage, and then sets her a test — to eat the flesh he tears from his own leg, or to grind and swallow the bones of the dead. The first two daughters die on the spot; the youngest only pretends to obey, hiding the bones and buying time.
The defeat is achieved by observation rather than force. The youngest asks her husband what he fears, receives the answer — cast iron and raw eggs — and keeps both ready for the decisive moment. Because the structure has the monster name its own weakness aloud, the one who wins is not the stronger party but the better listener.
On Jeju the narrative is transmitted alongside the taboos observed when a grave is moved or repaired. A real rule — that graves are not to be disturbed carelessly — survives in the shape of a story, which makes the tale a piece of horror and a procedure manual at once.