Seira is the future Mermaid Princess of the Indian Ocean (Sara's successor), and keeper of the Orange Pearl. Seira has three forms, Mermaid Seira, Human Seira, and her idol form, Orange Pearl Voice. Her image songs are Birth of Love and Beautiful Wish. She is a crucial role to the Pure season, but she hardly gets a full appearance until the end.

Spoiler

Her story starts off when Sara tells Lucia of her successor. Seira is going to be born, and Lucia is transported to the Indian Ocean, and with the Orange Pearl, the mermaid appears, but at that moment, Michel and the Black Beauty Sisters intervene. Lucia attempts to fight them, but because she is alone, she is defeated. Michel then takes this chance to absorb Seira's spirit into himself. Sara then tells Lucia that she must collect Seira's many heart fragments into the Orange Pearl before she can be fully born. This will take some time, because only one fragment might fall from Michel. In the meantime, Seira serves as Lucia's guidance and consciousness from inside the Orange Pearl. Lucia sometimes appears in a dream with her, and Seira gives her valuable information. Finally, during the battle versus Michel, he is nearly defeated, which causes all the heart fragments to scatter. With all of them in place, Seira can be born, and appears in front of the Mermaids as a full human. Her power helps them defeat Michel for good.