Will a half-mermaid, half-human girl bring an end to the feud between humanity and the mer-people? Or instead, bring about the destruction of all life on Earth? Shona returns to his birthplace to spawn and he meets a young human, Jimmy, who suffers from amnesia. Together, Jimmy and Shona set off to find the missing girl.

Will they be able to avert the mysterious prophecy, or will finding the secret of Jimmy's identity delay them enough to set Earth to destruct? This is the physical copy of the Tsuki no Ko (Moon Child) extended edition manhwa.