Lumina was born in the royal castle in Seagundia. As a baby, she wore a pearl bracelet with the royal crest. The only daughter of King Nereus and Queen Lorelei, Lumina was the rightful heir to the throne. Lumina's uncle, Galigo, wanted his son Fergis to inherit the throne. It was Caligo's dream to be king, so he wanted to live vicariously through his son. Caligo arranged for Scylla to kidnap Lumina in exchange for payment. Scylla found Lumina so endearing that she wanted to keep her safe from Caligo, so she raised Lumina on the outskirts of town in a sea cave. The king and queen were sad about Lumina vanishing and they locked themselves in the palace. Lorelei wore a locket with a picture of Lumina in it, but Lumina had nothing to remember her parents by because Scylla kept her pearl bracelet hidden. For seventeen years, the king and queen didn't perform their royal duties, and Lumina lived a peaceful but unexciting life with Scylla in their sea cave. She grew up believing Scylla was her aunt, and was never told about her origins because Scylla thought it would hurt Lumina to know the truth. Caligo convinced the king and queen to let Fergis be the heir to the throne now that he had come of age. There would be a royal ball for Fergis to meet a mermaid to be his queen, and King Nereus would give Fergis the royal medallion necklace, the Pearl of the Sea. After, the king would drink merberry nectar to toast Fergis. Caligo had become impatient waiting for the king and queen to die naturally, so he sent a messenger eel, Murray, to ask Scylla to poison the king's drink. Scylla feared that Lumina would be in danger if she didn't listen to Caligo, so she reluctantly agreed. Caligo planned to kill Scylla after she poisoned the king so that he would be hailed as a national hero. The Trident Squad, who would be guarding the ballroom, were loyal to Caligo and would assist him with his plan. Murray gave Scylla an invitation to the ball, and Lumina overheard them talking about the castle. Before Lumina could introduce herself to Murray, Scylla sent him away and hoped he hadn't realised who Lumina was. Lumina questioned Scylla about the castle, but Scylla told her it was too dangerous for Lumina to travel to Seagundia and refused to let her go. The next day, Scylla said goodbye to Lumina, but forgot her invitation. Lumina read it and realised Scylla was going to the ball, so she decided to go to Seagundia to give Scylla the invitation. Lumina packed some essentials into her pearl purse, left a note for Scylla explaining where she was, and set off with her best friend Kuda. At the castle, Murray mentioned to Caligo that he had seen a seventeen year old blonde girl, Lumina, when he spoke to Scylla. Murray suggested that Lumina could be a wife for Fergis, but Caligo thought that Scylla lived alone; he became suspicious that Lumina, from Murray's description, could be the princess. He sent Murray to bring Lumina to talk to him so he could question her. On their way to Seagundia, Lumina and Kuda entered a cavern with fire coral, a forest of kelp, and then followed a path until they encountered vampire squid. The squid were scared off by Spike, a stonefish that had poisonous spikes. He threatened Lumina and told her that one prick from his spikes could kill her, but she wanted to talk to him. To render him harmless she covered his thirteen spikes in pearls. She told him to be personable, but he found it hard to approach people because his appearance frightened others. Lumina understood how it felt to be lonely because of all her years alone at the sea cave with only Kuda and Scylla for company, so she befriended Spike and he went to the city with her and Kuda. Meanwhile, Murray went back to Scylla's sea cave, intending to kidnap Lumina. With Lumina out travelling, all Murray found was her pearl bracelet. After identifying the royal seal, he would use it as proof that Lumina was with Scylla. As Lumina travelled with her friends, Kuda swam into some SnarlyKelp, but Spike saved her. Kuda was shaken by what had happened and wanted to go home, but by then they had finally reached the city. Lumina got distracted as she looked around Seagundia, so she dropped Scylla's ball invitation without noticing. She found out she had dropped it when she tried to find it after spotting Scylla leaving a shop. Knowing she would get in trouble if Scylla saw them, Lumina hid in Salon La Mer, a hair and makeup salon. Kuda saw Scylla outside, so she and Lumina disguised themselves. Madame Ruchus, an octopus and the owner of the salon, was so impressed with how Lumina styled herself that she gave her a job. Lumina was excited, but had mixed reactions from her new co-workers : Sandrine, a half mermaid-half barracuda, was unwelcoming and told Lumina not to touch her things, such as her lucky hairbrush. Cora, a mermaid, was friendlier. Lumina's first client loved the look Lumina gave her using her pearl magic. The next day, Lumina was already favoured by clients. Murray showed Caligo Lumina's pearl bracelet with the royal crest. Caligo's plan would be affected by Lumina, so he ordered Murray to find her. Murray used his eel allies, Wormwood and Garth, to assist him. At Salon La Mer, they had a delivery from a merman prince named Deilphin who did deliveries as a hobby. He and Lumina got along, much to Cora and Sandrine's amusement. Madame Ruckus had been given invitations to the ball for the whole staff, so Madame Ruckus, Lumina, Kuda, Cora and Sandrine all went shopping for things to wear. Wormwood and Garth waited outside as Lumina looked at gowns in a shop. She couldn't find one to wear, but decided to worry about it later. As she left the shop, Wormwood and Garth tried to put Lumina in a sack, but the eels were knocked out the way by a carriage that Caligo and Fergis were in. Caligo and his son were also going shopping, and they had an appointment with Lumina at the salon. When Lumina returned to the salon, Sandrine softened up and let Lumina use her lucky hairbrush. Fergis came in for his session with Lumina, and she told him she would introduce him to Cora, who he had a crush on. She led Fergis to Cora to have his nails done, and hoped that they would become friends. After Salon La Mer closed for the day, Lumina's friends got ready for the ball and made her an outfit to wear. At the ball, Fergis was wearing a Quidest Fetere flower. It smelt bad, so Caligo removed it from him. As Lumina entered the ballroom, everyone stopped and stared. She danced with Prince Delphin, and Caligo realised that Lumina was the princess. He and Lumina went to an empty terrace, and Lumina and Kuda were put into sacks and thrown in the castle dungeon. Murray told Lumina that Scylla was going to poison the king, but Lumina was unsure of whether to believe him or not. Lumina used pearls to distract Murray and then escaped with Kuda. She wanted to help Scylla, even if she wasn't to be trusted. Lumina got away from guards by using her pearl powers, and Scylla put poison into Caligo's drink instead of the king's. The king and queen felt sad to be giving the Pearl of the Sea and the kingdom to Fergis rather than Lumina, but they put on a brave face. Scylla felt guilty after overhearing them discuss their feelings. She wanted to tell them about Lumina, but she wasn't allowed to speak to them. Caligo was suspicious about his drink, so he gave it to King Nereus. Scylla tried to stop the king from drinking it, but Lumina arrived in time and knocked the drink out of her father's hand. Caligo exclaimed that Lumina was trying to attack the king. All of Lumina's friends defended her, but Scylla admitted in front of all the guests that she had put poison in the king's goblet. Before Scylla could explain that she had been forced to poison the king by Caligo, Caligo pushed her into one of Spike's poisonous spikes. Lumina held Scylla in her arms as she grew weaker and weaker from the poison. Scylla finally told Lumina that she had taken her from her parents. Fergis pointed out his Quidest Fetere flower, the rare antidote to stonefish poison. Lumina placed two petals on Scylla's tongue, but the Trident Squad surrounded her. Lumina used her pearl powers more intensely than ever before to protect Scylla. The antidote worked, and Scylla told the king that Caligo was the one who told her to poison him. The Trident Squad tried to stop Caigo from being exposed, but Lumina and all her friends battled Caligo's guards. The king and queen's guards imprisoned Caligo and the Trident Squad after the struggle. Queen Lorelei told Lumina that her pearl magic is the royal gift, and Scylla revealed to Lorelei that Lumina is her missing daughter. King Nereus gave Lumina the Pearl of the Sea, making her the heir to the kingdom. Lumina's mother gave her a tiara. Even though Lumina had found her real family, she still considered Scylla to be her aunt. She wanted Scylla and Kuda to live in the castle with her. Lumina hugged her family and knew that the best dream come true wasn't being a princess, but being with the people she loved.
Lumina is a selfless and kind girl who sees the best in people. She loves to be creative and make things elaborate and extraordinary. Even though she had only had one friend, Kuda, her whole life, she was able to make friends very easily due to her personable nature. Lumina likes to help people and make them feel more confident, and she likes to see people thrive. She is very imaginative, which helps when she styles hair at Salon La Mer and plays Mermaid Princesses with Kuda.
Lumina has light skin, blue eyes and long blonde hair. She has a shiny tail, and she always wears a waist purse full of pearls. Usuaully, Lumina has a light blue and pink tail. She wears a pink and blue bandeau, and accessorises with pink and white pearls. In Salon La Mer, she temporarily had a short bob hairstyle. While shopping for attire for the ball, she tried on different outfits, but settled on a pink skirt and pearls to accessorise. When she transformed into a princess, her hair gained pink highlights and she got a tiara. Her tail became pink, orange and purple, and her skirt got longer. She was given the Pearl of the Sea, the royal medallion that has a large pearl in the middle.
- In Barbie Fairytopia: Magic of the Rainbow, there is a moon fairy named Lumina, but her name is pronounced differently. The name Lumina means "brilliant light". It is a Latin name.
- Lumina is the first character played by Barbie to physically be a mermaid all the time. She previously played Elina, a fairy who transformed into a mermaid, and Merliah Summers, a half human-half mermaid who uses a necklace to get a mermaid tail.
- Lumina is the only Barbie character to be seen with short hair.
- Lumina is the fifth princess to be initially unaware of her royal identity, following Princess Rapunzel, Princess Rosella, Merliah Summers, and Blair Willows/English.
- Lumina is the fifth character played by Barbie to have blonde hair with pink highlights. The first is Mariposa/English, the second is Thumbelina, the third is Merliah, and the fourth is Barbie herself in Barbie a fairy secret.
- Lumina is the fourth character played by Barbie to have a relative be the antagonist. The first being Princess Genevieve the second is Merliah Summers and the third being Blair Willows.
- In some pictures of Barbie the pearl princess's storybooks, she has no pink highlights in her mermaid princess form.