Xia Ling, Meiduo and Luo Qi are three ordinary girls living in a seaside town. They are not only classmates, but also close teammates of the band "Shining Girls". In a daily diving activity, they accidentally acquired the magical ability to turn into mermaids. Facing the increasingly bad marine ecology and the greedy predators who destroy the ocean for their own interests, the three girls decided to take action to protect this beautiful blue ocean on the earth with the power of love and mermaid!