On a gourd-shaped island where ancient civilization coexists with futuristic technology, a clumsy little mermaid named Gulu is rescued by a human boy named Yuwan after a mishap, thus beginning their intertwined and whimsically eventful lives. An adventurous, fantastical, and joyous journey is about to unfold. Can the little mermaid escape the numerous traps laid before her? How will Yuwan protect this mischievous spirit from the ocean?