A young girl named Namiko lives with her father Aranami, who was a protector and sailor in the sea. They live peacefully on the shore and have had a happy life...but Namiko's intense curiosity to travel and explore the sea has always been in the way! Aranami constantly warns her to not go into the sea without help...but on Namiko's 14th birthday...
Namiko recieved a letter. It was the prince of the sea, Taikai-Oji! From the urgency of the letter, he needed help. The sea has been in a violent tense discord from a megalomaniac corporate shrimp, pollution deliquents, and an "old friend" that he doesn't explain. For once, Aranami lets Namiko go...but with his old seagull familiar Umi Aprhoditone. Will Namiko solve the prince's problems?