The docks provide a look into the very essence of ocean life—the calm, rhythmic sounds of the waves, the small bugs skittering across the pier, and—mermaids!? Takurou Mukoujima's quiet days spent fishing are no more when he reels in the energetic mermaid Muromi-san, who proceeds to entertain herself around her newfound friend, even if he is obviously disinterested.

Now with a talkative and reckless companion always by his side, Takurou struggles to avoid getting caught up in Muromi-san's pace as she starts to invite her deep-sea friends, making the dock a popular gathering place for mythological creatures. Every day might be new and exciting, but all Takurou really wants is to fish in peace!