Watatsumi 海神 "sea god" or Ryūjin 龍神 "dragon god" was the ruler of seas and oceans, and described as a dragon capable of changing into human form. He lived in the undersea Ryūgū-jō 龍宮城 "dragon palace castle", where he kept the magical tide jewels.

YEH ♥♥♥♥♥ !