Kojin Okihiro cherishes the quietude of the sea—until a brazen mermaid shatters it. Eirin, a treasure-hoarding princess, loves to bewitch sailors into giving her their valuables. But when she targets Okihiro’s pendant, she faces an impossible challenge: he’s completely immune to her song.

Unwilling to accept defeat, Eirin vows to make him surrender the necklace—by any means necessary. But as her schemes grow wilder, Okihiro realizes that keeping his peace might mean facing the most unpredictable force of nature yet: a stubborn mermaid with no sense of personal space.

But as her pursuit drags on, Eirin finds herself doing something she never has before—learning how to communicate with someone. And as Okihiro watches the reckless mermaid carve out a space in his once-solitary world, both are forced to confront things they never really wished to recognize in this fun and wholesome retelling of a beloved classic.