Following the ultimate battle with Gaito, Sara perished in order to be with him. The underwater world is now tranquil, save for the six mermaid princesses. Although Caren, Noel, and Coco have gone back to their respective kingdoms, the time has come for Lucia, Hanon, and Rina to do the same. Mitsuki Tarou is departing for Germany, and Doumoto Kaito is on his way to Hawaii. Devastated, Lucia is hit with another misfortune as Kaito goes missing in the sea. Adding to that, a peculiar angel named Michel appears, urging the mermaids to join him. Nonetheless, there is a silver lining as Sara's spirit reveals a new mermaid named Seira, who will take her place. The mermaids embark on yet another thrilling journey. [less]