When Yuta unknowingly ate a piece of Mermaid flesh, he was granted immortaily. For 500 years, he traveled alone, search for a mermaid, so he could be mortal again. The day he finally finds some mermaids, they have a girl they plan to eat, because if they eat her, they become young and beautiful. Yuta kills them, while the girl eats the flesh of the mermaids. The girls name is Mana. Together, they try to look for a mermaid, just so they can return to their mortal states.