Ryūjin

Ryūjin or Ryōjin(龍神,"dragon god"), 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. Ryūjin 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 Ryūjin's servants.