Ryujun, also known as Ōwatatsumi, was the tutelary deity of the sea in Japanese mythology. This Japanese dragon symbolized the power of the ocean, had a large mouth, and was able to transform into a human shape.
Ryujin lived in Ryūgū-jō, his palace under the sea built out of red and white coral, from where he controlled the tides with magical tide jewels. Sea turtles, fish and jellyfish are often depicted as Ryujin's servants.
Ryujin was the father of the beautiful goddess Otohime who married the hunter prince Hoori. The first Emperor of Japan, Emperor Jimmu, is said to have been a grandson of Otohime and Hoori's. Thus, Ryujin is said to be one of the ancestors of the Japanese imperial dynasty.