Sea Story

The two "pure" mermaid sisters Marin and Urin, who dwell in the sea with the fish yet wish to be above the water, are the main characters of the novel. One day, Marin and Urin find a stunning ring that has fallen into the ocean. For the first time, the two decide to depart from their underwater world in order to present the ring. They arrive at a remote island where a high school student named Kanon dwells after a difficult voyage. Only Marin and Kanon, as priestesses of the sea and the sky, are capable of defeating Sedna, a powerful entity sealed long ago on the island and in the sea, after Urin unintentionally releases her. The sisters, under the guidance of the Elder Turtle, battle a variety of marine creatures that Sedna has turned into monsters, but Urin's rising resentment of Kanon and her lack of independence cause Sedna to corrupt her. In her capacity as Sedna's host body and the priestess of evil, Urin releases Sedna's sea half to give her back her full power and makes Marin and Kanon her foes. Marin loses her abilities due to the devastation of losing her sister and her own incapacity to deal with the dark. Similar to Kanon, Kojima is her distant ex-boyfriend who she is afraid of developing genuine connections with and alienating.