Mermaid Melody

Plot
Luchia, the mermaid princess of the North Pacific Ocean, sets out to land to find the boy she saved from a tsunami wave seven years before the beginning of the story, to whom she had entrusted her pink pearl. She eventually finds the boy: a surfer named Kaito Dōmoto. But Kaito does not recognize her in her human form. She cannot tell Kaito who she really is; otherwise, according to mermaid legend, she would turn into seafoam. She tries to convince Kaito into figuring out who she really is (since the legend does not say anything about the other person discovering a mermaid's true identity by himself).

At the same time, Luchia has been told that a group of water demons have invaded the sea world and she must gather six other Mermaid Princesses and their pearls to bring back the legendary goddess, Aqua Regina, to stop them. To fulfill this, she joins forces with Hanon and Rina, the Mermaid Princesses who came up to dry land, use their pearls, turn into singing teen idols, and use their voices as an offensive power.

Sara had forgiven Tarō Mitsuki for the mistakes he made in the past (her hate for him disappeared and her black hair reverted to its orange color). But since she became such a close friend to Gaito and she wanted to share his fate for everything he has done, she decided to entrust her orange pearl to Lucia and join Gaito in his demise. The Marine World may go back to normal, but it has one less Mermaid Princess.

Plot
Enter Seira, the new owner of the orange pearl. But she's not born yet; just a spirit who appears to Lucia in her dreams. In order for Seira to be born, her heart (心, kokoro) must merge with the orange pearl. But even before this happens, her heart is stolen by an angel named Michel. Luchia (together with Hanon and Rina) must retrieve pieces of her heart, even if she will face an almost unbeatable foe.

On the other hand, Kaito and Luchia love each other more, especially that Kaito has finally figured out that she is the mermaid who rescued him seven years before. But they are about to be separated once again when Kaito bounds for Hawaii to continue searching for the truth about his identity. But while in Hawaii, a surfing accident erases all of his memories. He is found and tended by a girl who has feelings for him. Luchia has to cope with this shock and attempt to let him remember at least some of his memories, especially of her.

Along with Luchia's romantic troubles, this season also highlights Hanon and Rina's love stories. Hanon rejects a persistent suitor, but finds newfound love with him after her fixation with her music teacher, Tarō Mitsuki, ends in disappointment. The story also covers Rina's first experience of love...

Many new villains and villainesses appear, including the return of some older characters. This season also features songs for the villains as well as newer ones for the mermaids.