Marin Asagi is a cheerful and curious sea dweller from the anime series "Umi Monogatari: Anata ga Ite Kureta Koto." As a main protagonist, Marin is a mermaid who ventures to the sky realm after discovering a ring that has fallen into the sea. Her innocence and determination lead her to form a strong bond with Kanon, a human girl. Together, they embark on a journey to purify the darkness that threatens both their worlds, showcasing Marin's kind-hearted nature and her ability to see the good in others.