Tập 1: Mana, 15 tuổi, trốn khỏi ngôi làng của những nàng tiên cá bất tử cùng Yuta sau khi biết được số phận của mình.

1

In a mountain village from Setouchi region, Mana has just turned fifteen. She is cared for and pampered by Baba, an old woman who keeps her shackled in bed. The village is inhabited by identical old and young women who are all mermaids in human form. Meanwhile, Yuta, a young man arrives, looking for a mermaid. He is actually a 500 year old immortal human who became so after eating mermaid flesh. One of the women is chosen by the others to become a mermaid by entering the ocean and she is then sacrificed. Baba feeds her flesh to Mana to make her an immortal human whose flesh will rejuvenate the old women. Yuta learns of their plan and escapes with Mana after explaining her fate. The women try to stop Yuta and Mana from escaping, but they are caught in flooding sea water and revert to their mermaid forms. Baba, who is an immortal human, not a mermaid, decides to stay with the mermaids who are unable to take human form again. As Yuta leaves with Mana, he tells her that life as an immortal isn't all bad, although he still hopes to become mortal again. (Source: Wikipedia)