TV-Series
Description
Marin is a sea dweller who lives alongside fish beneath the ocean, one of the two central protagonists of the story. She was born from a shell, a trait common among the people of the sea, meaning she does not have parents in the human sense. She considers Urin her younger sister and shows her constant affection, despite the fact that the sea people do not form nuclear families. Marin's life changes when a beautiful ring falls into the sea; she finds it and grows curious about its owner. This curiosity inspires her to leave her underwater home for the first time, accompanied by Urin, and travel to the land above. There she meets Kanon, a high school girl who turns out to be the ring's owner.

When Urin accidentally releases the sealed entity Sedna, Marin learns that she is the next priestess of the sea. In this role, she gains the ability to fight the monsters Sedna creates, working alongside Kanon, who becomes the priestess of the sky. Marin is warm, caring, and deeply attached to Urin, whom she protects and dotes on. However, her initial goodness is not hardened against darkness; when Urin is corrupted and becomes Sedna's vessel, Marin is overwhelmed by despair and loses her powers. She struggles with fear and the inability to cope with the idea that her beloved sister might be lost forever. With Kanon's support and encouragement, she confronts her own insecurity, regains her abilities, and resolves to save Urin rather than destroy Sedna outright.

Marin's key relationships are with Urin, her sister and constant companion; Kanon, her fellow priestess and friend; and the Elder Turtle, an ancient being who advises both girls. She also lives alongside other sea friends Sam and Warin, who provide companionship. Throughout the story, Marin grows from a naive, curious girl into a more mature individual who understands that darkness is not simply evil but a part of human nature that must be accepted. She ultimately helps the islanders embrace Sedna's sorrow, freeing Urin and allowing Sedna to dissolve peacefully. Her notable abilities include commanding sea magic, transforming into a priestess form (using enchanted stones), and fighting monsters. She also possesses a strong emotional connection that enables her to empathize with others, a quality that proves essential in the final resolution. Marin and Urin eventually return to the sea, but the bond she formed with Kanon remains significant.