Umi Monogatari is an anime series that follows the story of Marin and Urin, two sisters from the sea who venture onto land. Their journey leads them to encounter a young girl named Kanon who is struggling with personal issues. Together, they confront a dark force threatening both the sea and the land. The series explores themes of friendship, self-discovery, and the connection between the ocean and human emotions. It originally aired in 2009, capturing audiences with its magical and heartfelt narrative.