Its first attested appearance is in Sekien’s Konjaku Hyakki Shūi, where the caption simply notes it eats fish by the river. No distinct folktale type has been identified. Some have compared it to a Yamaguchi dialect creature called Takiwaro that becomes an enko (kappa) upon entering the sea, but any direct lineage is unclear. Modern reference works typically present it as a yokai originating from art, without local tradition attached.