During the series will face the devils water and must meet the seven princesses sirens to summon the Water Queen. With its pearls can become as a singer and use their voices to defeat their enemies through song. The first opening theme, "Taiyo no Rakuen ~Promised Land~" by Miyuki Kanbe, and the first ending theme "Daiji na Takarabako"(Important Treasure Box) by Asumi Nakata.
The series is about Luchia Nanami, a mermaid princess with his partner Hippo in search of pink Pearl to reach adulthood, which gave a child who escaped the sinking of a liner. Upon reaching land staying at the hotel Perla where they reside Nikora and Madame Taki, during a walk on the beach meets Kaito Doumoto, the boy who saved for years, but not recognized because to his human form is different from the way siren.