The Mermaid Princess is a character making her debut in the storybook of The Mermaid Princess. She is only seen in A Happy Mermaid Princess.
The Mermaid Princess appears as a tall girl with blonde hair, peach skin and teal eyes. In her mermaid form, she lacked legs instead had a tail. While In her human form, she wore a teal dress.
The Mermaid Princess was shown to be sweet and innocent, though she was shown to be reckless to get her humanity. She also shows a withdrawn and shy personality. She also takes a liking toward Doraemon, despite his intentions to get her married to the Prince as she should.
The Mermaid Princess is the titular protagonist of a storybook. In the story she has been granted permission by the Queen to rise up to the surface of the sea to see the upper world, sees a prince on a ship, and falls in love with him from a safe distance. A violent storm hits, sinking the ship, and she saves the prince from drowning. She delivers him unconscious to the shore, waiting until a young woman from another country and her servants find him.
If Doraemon had not intervened, she would have been given a potion from a witch to turn her tail into a pair of legs in exchange for her voice so she could see the prince once more. However, the prince was engaged to a princess from another country. The Mermaid Princess could have killed the prince to save her life, but she could not help to do so. She took her own life by throwing herself into the water and dissolving into foam.
But then, Doraemon enters the story and intervened while the mermaid was about to receive the potion and is given a pair of legs in exchange for her starfish headpin. The mermaid, while getting to know Doraemon, meets the prince and they had fun around the park. However, that does not change the ending as she still ends her life dissolved into foam. Doraemon enters the story once again and finds out the neighboring princess is going to marry the prince. He is unable to convince that it was actually the mermaid princess who saved the prince, and she leaves the castle devastated. Having developed feelings for Doraemon throughout the story, she proposes to him, but Doraemon comes to his senses and reveals he was just trying to make the mermaid princess and the prince be together. Feeling Doraemon had rejected her, the princess jumps in the river.
Doraemon later changes the story once more by going back to the beginning and making sure the princess of the other country never finds the prince and also forces the mermaid princess to tell prince the truth. She marries the prince in the end.
- She is the only human known love interest of Doraemon. While his other love interests are cats or cat-modeled robots.