They say that if one consumes mermaid flesh, one can attain immortality. Unfortunately, the more likely results include becoming horribly deformed or turning into a vicious monster! Even if one were to gain eternal life, however, is such an anomaly a lucky blessing or a terrible curse?

Yuta became immortal when he unwittingly ate mermaid flesh, and now he seeks a way to become human again. Hundreds of years later, he encounters a volatile and determined young lady named Mana while searching for a mermaid. Could this mysterious woman hold the key to saving Yuta's humanity?