Umi Monogatari

Sea Story: That You Were There For Me (うみものがたり 〜あなたがいてくれたコト〜, Umi Monogatari ~Anata ga Ite Kureta Koto~) is a Japanese episode anime series directed by Junichi Sato and produced by Zexcs. It began airing on Chubu-Nippon Broadcasting on June 24, 2009 for a span of 12 episodes. An unaired 13th episode was featured in the final DVD volume, released on March 26, 2010. The anime is based on a pachinko game manufactured by Sanyo Bussan.

Plot
Marin and Urin, two “pure” sisters who live alongside the fish in the sea, but yearn to be in the world beyond the water and above ground. One day, a beautiful ring falls in the middle of the sea, and Marin and Urin retrieve it. The two decide to leave their waterbound world for the first time to deliver the ring. After an arduous journey, they come across an isolated island where a high school girl named Kanon lives. Accidentally, Urin unleashes a power sealed long time ago in the island, and the only ones who can defeat it are Marin and Kanon, as priestesses of the sea and the sky.