Sophia has blue hair and aquamarine eyes. She wears a yellow tiara headband with a ruby on top with five lines, like a pentagon. She also wears a pink "mermaid suit", complete with a sliver "mermaid transformation belt with a "Y" on the yellow center. In both forms, she wears arm warmers and a pink top with white markings on top.
In her human form, she wears a white skirt with white leg warmers and pink shoes. However in her mermaid form, She has a light pink tail with pale pink tail fins at the end of them.
She wears two pigtails/braids on her blue long hime cut hair. In her princess attire, she has a pair yellow Y clips with white pearls on her odangos on top of her hair without the tiara. She also wears a white dress with pink markings under white short sleeves and a pink skirt under the puffs of her dress. She also wears sandals, and wears a white pearl-centered red necklace.
Sophia is a kind and sort of tomboyish (at least when compared to Shizuka) mermaid princess.
After the Underwater Pump Stimulator, complete with Seawater Survival Gas went off, along with Nobita and Doraemon taking off their water goggles off, a mermaid inadvertently landed in Nobita's backyard, her name was Sophia, who turned out to be the Princess of the Aquarians. When Nobita and Doraemon first saw her, they thought that she was cute. After drinking juice, She speaks Aquarian language, a fictional language spoken on the planet, Aqua. Doraemon and Nobita couldn't understand her own language, so they used the Translation Tool to understand her their language. After that, she mistook Doraemon for a puffer fish. And then she introduced herself as Sophia. And so, Nobita and Doraemon, Suneo, Shizuka, Gian went on a mission to find the mysterious weapon called "The Mermaid Sword" ( from Sophia's tiara) in order restore peace to the sea.
Suneo is showing off again, this time about how he’s been going scuba diving and swimming with ocean life. Of course, Nobita is jealous as usual and asks Doraemon for help. Doraemon pulls out an ocean simulator that lets anyone wearing the goggles to actually simulate diving. They leave the machine pumping water for the night and then go around town scattering some fish food, ready to invite some real ocean life to take pictures with and brag about.
After a fun night out, the next morning they find a girl who turns out to be Princess Sofia of the Aquarians. She got lost through one of the portals Doraemon had set up but was amazed at the surface world. After a tour and meeting Nobita’s friends, she explains that her people migrated from Planet Aqua to Earth 5000 years ago – about the time when stories about mermaids first emerged on Earth. Now they live quietly in the deep seas. When she decides to return to the palace, Nobita and his friends join her with some help of Doraemon’s gadgets. On their way back, they are attacked and are mistaken as kidnappers. Shizuka manages to hide but she is abducted by the Aquarian’s enemy, the Kaiges who managed to track them down, determined to get their hands on the legendary sword. After Sofia clears up the misunderstanding, they have an audience with the queen Ordeen who tells them how their fight with the Kaige had made their Planet Aqua uninhabitable. A message arrives from the Kaige demanding they hand over the sword in exchange for Shizuka who was being held hostage. Unable to decipher the clue they had found, they didn’t know the whereabouts of the real sword so they decide to create a decoy. There was little time left before the effects of the underwater gun was going to expire. They rescue her just in time and a fight breaks out. As Sofia prays for help, the sword reveals itself and the Kaige’s leader Buikin obtains the power, making quick work of Sofia’s army.
After luring him out of the water, Sofia and the others manage to trap Buikin using Doraemon’s simulator. In the process, they find out the sword helps clear up polluted water and Sofia is happy they can return home to use it on their home planet. The heroes are welcomed back with cheers in the kingdom but they Nobita and his friends realize they’ve away for too long.
With that, they say farewell and take the time machine back to before they met Sofia, ready to return to their everyday lives and wondering if they will ever meet again.
Nobita is Sophia's temporary love interest.
Shizuka is Sophia's "girly girl" friend.
- Sophia is the only princess in the entire Doraemon franchise who was based on a mythical creature.
- Sophia's name comes from Latin spelling of the Greek name "Σοφια" (Sophia). In Greek, "σοφία" (Sophia) means "wisdom, art".
- The ancient mermaid warrior in the movie is also named Sophia.