In a mystical realm that exists beneath the human world, populated by magical-powered beings, a girl named Chun participates in a coming-of-age ritual where she is transported through a portal of water to experience the human world in the form of a red dolphin. There, she encounters a human boy who lives by the sea and reveres aquatic creatures. During a storm, Chun is tangled in a fishing net near the boy's house, and the boy drowns while freeing her from the net. Chun returns to her world, taking the boy's ocarina with her.