Anastasia is an antagonist that appears in Castle of Dreams in Kingdom Hearts Birth by Sleep. One of Cinderella's evil stepsisters, she would do all in her power to make Cinderella's life miserable and to marry the handsome Prince Charming. She came from the Disney film, Cinderella, but despite being one of the film's main antagonists, she is not a boss in the Kingdom Hearts series.
 Kingdom Hearts Birth by Sleep
When a ball is held at the Castle of Dreams, all unmarried women are invited for the prince to find a bride. Anastasia, along with Drizella and Lady Tremaine, attempted to keep Cinderella from going along by giving her endless chores to finish and preventing her from finding a suitable dress.
When Ven and Jaq make it for her, she and Drizella tear it apart saying she had stolen their materials. But their plot failed when the Fairy Godmother makes a new dress for her and a pumpkin carriage to transport her to the ball. She is unable to identify Cinderella during the party as she is too far away from Anastasia to be recognized. Her anger at having to watch the Prince dance with an unknown woman contributed to the summoning of the Symphony Master, which was defeated by Terra.
After the ball, Prince Charming asks the Grand Duke to search for Cinderella with the glass slipper. When he finally reaches their house, Anastasia attempts to make the shoe fit her oversized foot, but Cinderella proves to be the true owner of the slipper. The Duke takes Cinderella with him back to the Castle, only to be confronted by Lady Tremaine and a powerful Unversed who intend to murder Cinderella, knowing that she is now free from them. This act, however, causes the three women to be hit by one of the Unversed's attacks and suffer an unknown fate. Aqua then states that they were overtaken by the darkness in their hearts.
Anastasia is a thin young woman with a round face and nose and creases on either side of her nose, the latter a feature she shares with her mother and sister. Her skin is pale and she has brown eyes. Her hair is long, orange, and worn with short, neatly-cut bangs over her forehead and several curls in the back.
Anastasia is only seen in her formal attire during Kingdom Hearts Birth by Sleep. This consists of a ballroom gown colored mostly in shades of pink with a violet top and choker, as well as two pink, puffy, disk-like pieces of cloth over her shoulders. She also wears a headband with a large, pale green feather on it.
Much like her older sister, Anastasia is shown to be spoiled, selfish, cruel, and lazy. She will do anything to get her own way, even to the point in which she turns to the darkness in her heart. She sometimes fights with Drizella. Anastasia strongly hates Cinderella because of her beauty, and takes great pleasure in bullying her.
Despite her selfishness, she is very loyal to her mother. According to her journal entry, she is shown to play the flute very poorly, but she still takes pride in it.
Anastasia first appeared in the 1950 Disney film, Cinderella. She was cruel and unkind to Cinderella, and does not want her to go to the ball. When the footman tries to fit the glass slipper on Anastasia's foot, she at first thinks her foot fits, but it does not. Anastasia later appears in the film's sequels, Cinderella II: Dreams Come True and Cinderella III: A Twist in Time, as well as the TV series, Disney's House of Mouse. In the sequels, she gradually becomes nicer and less antagonistic as she attempts to find her own true love.
While she played an antagonist role in the first film, she was a protagonist in the third film, with her mother trying to get Prince Charming to fall in love with her.
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