After saving a nearly drowned boy, Mermaid Princess Lucia of the North Pacific Ocean Kingdom leaves her magic pearl in his custody. Seven years later she takes on human form and with the help of her guardian penguin, Hippo attempts to find that boy and reclaim her magic pearl. When she first meets up with the boy, Kaito she thinks he is rude, but when he is threatened by the undersea villains she reclaims her pearl and transforms into Pink Pearl Voice and defeats the villain by singing at her. After the fight Lucia (in her mermaid form) holds Kaito in her arms like she did 7 years ago, and from there realized the feelings she has for him. But unfortunately for her, mermaids or not allowed to love humans. In order to stop the coming evil Lucia must revive the Aqua Goddess Regina. In order for this to be done she must find the other 6 Mermaid Princess.