Seira's story begins when Lucia hears a child's voice in her dreams, calling for help. Following the source of these mysterious pleas, Lucia dreams that she journeys to the ruins of the Indian Ocean kingdom. There she meets the ghost of Sara, surrounded by tiny spheres of light. Sara explains what the mysterious lights are:
The life breath of the Indian Ocean is forming into spheres of light. These are all gathering together... These spheres of light are called "fragments of the heart." They are necessary for Seira to be born, not just as a mermaid, but as a woman. Love, and friendship, and the power of belief are being gathered into the heart of this girl.
Unfortunately, the extraordinary energy of Seira's "fragments of the heart" are coveted by another: a villainous creature named Michel. He attacks the yet-unborn Seira, stealing the fragments of her heart. Now Lucia must pursue Michel and fight to reclaim the fragments of Seira's heart. Lucia carries the Orange Pearl with her everywhere. When she finds another fragment of Seira's heart, it is absorbed inside the Orange Pearl, and Seira learns how to feel an emotion like love, friendship, or belief in another.During most of the second story arc, Seira seems to exist inside of the Orange Pearl. She can appear before Lucia as an insubstantial spirit, usually to offer encouragement when Lucia is feeling down. When Seira is first introduced in chapter 21, she comes across as somewhat of a brat - and she is, even taking into account her age. For example, she taunts Lucia for crying about Kaito. However, as the manga progresses, and as Seira learns more about love and friendship, she matures greatly. Seira may still be just a little girl, but she comes to understand Lucia's feelings on a profound level. Eventually, Seira becomes Lucia's staunchest supporter.
A Ray of Hope
In chapter 28 of the manga, Seira's spirit-form is absorbed into Michel. Within Michel's heart, Seira tastes profound sadness and loneliness for the first time. And yet, buried beneath Michel's rage and hatred, Seira discovers something else - a "crying voice," as she describes it.
SEIRA: I can feel your sadness... I can hear a voice inside of you, crying out to be saved from this sadness! I can hear a tiny voice crying out, a voice that still believes in this world!
MICHEL: That is only your OWN cry that you hear, and nothing more!
Still, Seira refuses to give up. She begs Lucia and Kaito to "save" Michel, and continually pleads with Michel to realize that he is not alone. Finally, however, the climatic moment arrives. Seira confesses that she cares about Michel, and Michel, in turn, realizes that - unbelievably - there is somebody who loves him.
Unfortunately for Michel, this realization seems to come too late.
The Birth of a Princess
As his castle - and his entire dimension - crumbles around him, Michel sets free Seira's spirit-form, and all of the "spheres of light" (that is, fragments of her heart) that he had stolen from her. He tells Seira to leave, and thanks her for her kindness. Although Seira doesn't want to leave Michel's side, Fuku-chan forces her away. Seira and her spheres of light tumble from Michel's realm of the sky down to the Earth below. Then the spheres of light combine together, and Seira is finally, truly born into the world.
But the battle isn't over. Fuku-chan follows Seira and the mermaid princesses down to Earth, and, overwhelming Michel's will, uses the angelic being as a puppet who attempts to hunt down and destroy the princesses and their allies. Even when confronted with an evil, soul-less Michel, however, Seira's heart aches for him. "Michel really truly is a nice person, just like Michal!" Seira tells Lucia. Seira wants nothing more than to save Michel from Fuku; and with Lucia's help, ultimately, the strength of Seira's love for the forlorn angel is enough to do so.
It is telling that when his moment of salvation comes, Michel's final words of farewell are to Seira, and to Seira only. "Believe that we will meet again someday..." Seira weeps tears of mixed joy and grief as Michel leaves her.Seira ultimately proves herself a profoundly kind, gentle, yet strong person. Her experiences sharing Lucia's emotions, and then Michel's emotions, have taught Seira many things about the strength of love, and the pain of loneliness. During the climax of chapter 30, watching Seira's determination to save Michel during the final battle, Coco even comments, "Sara... The little princess of your kingdom has already become a wonderful friend."
Seira's Forms
mermaid Seira
This is Seira's basic, true shape (first appearance: chapter 21).
human Seira
Seira appears as a human in the color illustration the prefaces chapter 24. She does not, however, actually appear as a human within the actual storyline of the manga, until chapter 30.
Orange Pearl Voice
Seira's superheroine alter-ego (first appearance: chapter 29).
Seira's Powers: Pre-Birth
spirit manifestation - insubstantial
Seira can manifest herself as a ghost or a spirit, but only in her mermaid form.
communication
Seira can communicate to Lucia telepathically, or via dreams. She can also pray to Aqua Regina, and the ocean goddess appears to hear Seira's prayers.
light
When Lucia is feeling down, Seira can make her Orange Pearl glow with a bright, warm light. This seems to have the effect of cheering Lucia up.
spirit manifestation - substantial
In chapter 27, Seira reclaims some of the fragments of her heart from Michel, pulls them into herself, and manifests herself as a very solid, substantial "spirit" form of her mermaid self. Despite the fact that her body appears solid, however, she has not yet been truly "born".
staircase
In chapter 28, in order to allow Lucia/Hanon/Rina to escape Michel, Seira creates a magical staircase that sends the mermaid princesses and Kaito to a distant beach.
Seira's Powers: Post-Birth
transformation
Seira does not use a special phrase or incantation to transform into Orange Pearl Voice; she just does.
singing
Even in her mermaid form (that is, without transforming into her idol form), Seira can sing a song so powerful and moving that it can be heard all over the world - and even in the darkest depths of the ocean's bottom.
Magical Items
Orange Pearl
The Orange Pearl is the source of Seira's power; she needs it to transform into Orange Pearl Voice. In addition, before she was born, Seira existed as a spirit inside of her Orange Pearl.
seashell locket
Like the other mermaids, Seira keeps her pearl in a seashell locket that she wears around her neck. Her locket is orange in color.
microphone
When she transforms into Orange Pearl Voice, Seira uses her microphone to project her singing voice.