Luchia, the Mermaid Princess of the North Pacific Ocean, keeper of the pink pearl, and the main character of the story. She goes up to land to search for a boy she saved seven years ago. She is unaware of the danger in the marine world and of her real mission until she is told of them by her "older sister", Nikora. She is characterized by her simplicity and naïveté, but with having a strong will, typical traits of shōjo manga heroines. Her idol form is Pink Pearl Voice. Of all the mermaids in the series, Luchia's mermaid form and human form contrast the most (Luchia has dark blonde hair and brown eyes in the surface while having lighter blonde hair and light blue eyes while at sea).
Hanon is the Mermaid Princess of the South Atlantic Ocean and keeper of the aqua (水色 mizu-iro "water-color") pearl. Unlike Lucia, Hanon goes up to land to escape water creatures. She is perky and feminine, yet a bit more worldly than her friend Lucia. This worldliness is evidenced by many of her actions—especially by her romantic pursuit of her music teacher, Tarō Mitsuki. Her idol form is Mizuiro (Aqua) Pearl Voice, although the first time that it is named in the manga, she is erroneously called Blue Pearl Voice.
Rina is the Mermaid Princess of the North Atlantic Ocean and keeper of the green pearl. Initially she is depicted as beautiful but stern and bent on revenge for the capture of her best friend, Noel. Later, however, she evolves into a more mature character, and acts as an older sister figure to Lucia and Hanon. She seems to love plasma TVs and shows this love in many anime episodes. Her idol form is Green Pearl Voice.
Some fans in the West still spell her name as Lina, because the Japanese language does not distinguish the sounds "r" and "l", treating them as the same. This means that "ri" and "li" are both represented as リ, and it can be difficult to figure out what the intended romanization is until it is established by official sources.
Karen is the Mermaid Princess of the Antarctic Ocean, keeper of the purple pearl, and twin sister of Noel. In the anime, she first appears as the winner of a beauty contest that the main trio enters; in the manga, she first appears to save them from the Dark Lovers. In the first season, Tarō asks her about his mermaid, and she later blames Rina for Noel's kidnapping. Even after things are straightened out, she chooses to go find Noel alone. She is Noel's polar opposite, having a mysterious personality. Karen and Noel are twins, born on opposite sides of the Earth. When Karen finally meets Noel, she launches herself at Noel, hugging her and calling her Onee-sama, a respectful term for big sister. Even though the two had not met before, Caren cares most for Noel and would do anything to save her, even if it meant Karen having to find here on her own. While she is cold and distant in the first season, she is found to be wild, humorous, and even a bit strange in the second. Her idol form is Purple Pearl Voice.
Noel is the Mermaid Princess of the Arctic Ocean and keeper of the deep blue (i.e. 藍色, ai-iro) pearl. She helped Rina escape from the sea monsters, which led to her capture. She is calm, gentle, caring, and studious (as she sometimes wears glasses on land later in the second season of the anime). She is Caren's older twin sister by about a minute at the most. Noel cares deeply for Caren, the one that she had always wanted to meet. Her idol form is Ai-iro (Deep Blue) Pearl Voice.
Coco is the Mermaid Princess of the South Pacific Ocean and keeper of the yellow pearl. She is incarcerated by the sea monsters for most of the first season, so not much is known about her. In the manga, however, she is a friend of fellow Mermaid Princess Sara. Later, she found to be playful and gentle in the manga, yet brash and outspoken in the anime. Her idol form is Yellow Pearl Voice(The group creators personal favorite mermaid :DD)
Sara is the Mermaid Princess of the Indian Ocean and keeper of the orange pearl. She joins Gakuto in his quest to take over the marine world after an incident bestowed her a dark power, turning both her orange hair and her orange pearl pitch black (though her eyes stay orange) and destroying her own kingdom. That incident was a proposed rendezvous with Tarō, her secret human lover, in which he never showed up. (In the manga, he actually arrived before, but Sara's guardian found out about the relationship and insisted that he leave, convincing Sara that he had abandoned her.) In a fury, Sara unleashed a wave of power, destroying her kingdom and causing the wave which killed Kaito's parents and from which Lucia saved Kaito. In the manga, her villain name is Black Pearl Voice and she transforms into an idol in a black dress reminiscent of a diva. However, in the anime, she does not transform until she turns good, and instead has the power to sing offensively in a humanoid, amphibious form like the villains and mermaid idols, with or without her E-pitch. In the end, she decides to join the other mermaids as is her duty. She, herself, seals the gate to Gakto's castle in the book because it's her duty and she unsealed the gate after her kingdom was destroyed. In the TV show, Aqua Regina seals the gate and Sara goes with Gaito because she loves him. The manga shows that she goes with him because she realizes that he is the one that needs her the most and that what he did was partly out of love for her and the want to make her happy. She also appears in the second season as a spirit, informing Lucia of the future Orange Pearl Voice and offering her assistance where she can. Sara is also seen singing with the other mermaid princesses in the very last episode of Mermaid Melody Pichi Pichi Pitch Pure.
Seira is the future Mermaid Princess of the Indian Ocean and future keeper of the orange pearl. She appears as a spirit to Lucia, taking the form of a young mermaid. When her time of birth finally came, Michel seized his chance and absorbed Seira into his body, and her birth was therefore delayed until Lucia can retrieve all the pieces of her heart contained in Michel's feathers. Every time Lucia retrieves a piece of her heart from one of Michel's fallen feathers, Seira learns something about an emotion, such as love or friendship. Once born, she is destined to become Orange Pearl Voice. Seira is very child-like and sees the good in Michel, realizing that he has good intentions for the earth.
Izuru is the most mature of the four, she has the power to control waves and marine beasts and has the ability to create dragons from water. She is also the most obsessed with winning the heart of Gakuto.
Eriru is the one with the multiple personality disorder. At one phase, she is cute, beady-eyed, and acting as if she were antsy (spinning around and never saying any normal speech). In another phase she can speak correctly and is more observant of her surroundings. In her third phase, when threatened (or when she spins around), she becomes scary, her eyes glow red, and she changes her voice accordingly.
Yūri is the youngest-looking of the four. She has the ability to control people and objects, especially with the use of her music and, if any, a nearby piano. Although Yūri is loyal to Gakuto, his continued treatment of her as a child leads her to a star-crossed relationship with Hippo, i.e. his human form.
Maria is the one closest to Gakuto in terms of love. She is also very cruel at times, and sometimes seems to see Gakuto more as a boy-toy than a love prospect. She has the power to make and/or manipulate ice and snow.
They're composed of the red-wearing older sister Sheshe (シスターシェシェ, Shisutā Sheshe?, Voiced by: Miki Tsuchiya) and the blue-wearing younger sister Mimi (シスターミミ, Shisutā Mimi?, Voiced by: Noriko Shitaya). Gakuto hires them after the Dark Lovers' failed attempts to capture the Mermaid Princesses. These two have the ability to sing tunes more powerful than the songs the Mermaid Princesses themselves sing, although in the anime and the second arc of the manga, the Princesses manage to get strong enough to overpower them. Though Gakuto turned them back to their original forms (two angler fishes), they were brought back in the second season. Their group name is usually shortened by fans to BBS.
Lady Bat calls himself "The wings of love and pleasure." Michel's vampire-like servant. His song hypnotizes the listeners into his spell so he could "bite" the person while they are asleep. There is certain controversy about his real gender, especially among fans in the West; in the manga, Lady Bat is actually a man wearing women's clothes. He is also strong enough to bring the Idol-formed Princesses back into Mermaid-form. (The group creators uber favorite villain/male anime character <3)
Lanhua calls herself "The wings of desire and contentment." Michel's butterfly-like servant. She can divide into a dozen smaller versions of herself (which really do not look harmful or dangerous; in fact, very cute) to play a tune that makes the listeners dance until they die. She is called Ranfa and Lang Fa in some merchandise, but the translators for the manga followed the Mandarin Chinese pronunciation of her name and called her Lanhua.
Alala calls herself "The wings of dreams and decadence." Michel's fairy-like servant. She sings two songs in the anime; a peppy song that shoots stars at the Princesses and a sugary sweet song that makes men cheer for her. In the manga, she can make people (or at least a Mermaid Princess) dream about anything she wishes, including nightmares. Her name seems to come from the Spanish words La ala, when switched would be "Ala la", together making Alala. La ala means the wing.
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