Turban-shell demon changed after thirty years
Sazae-oni
After thirty years under the sea, the shell opens arms and legs to the moon. Do not stare too long at the woman dancing on the water.
Overview
Sazae-oni is a yokai said to be a turban shell that lived thirty years and gained magical power. It may float and dance on moonlit seas, and later tales say it becomes a beautiful woman who deceives pirates.
Encounter
On a bright moonlit sea, a white form rises and dances with limbs extended. In Nakiri, it appears as a beautiful drowning woman taken aboard by pirates, only to reveal its true nature.
Lore
Toriyama Sekien drew Sazae-oni in Hyakki Tsurezure Bukuro in 1784, citing a passage from the Liji about creatures transforming. Later coastal stories were shaped by modern retellings.
Traits
It hides deep in the sea and may transform into a woman. In the pirate tale, it mutilates the men who approach it and demands gold in exchange.
Sparrows enter the sea and become clams; field mice change into quails.
Hyakki Tsurezure Bukuro