She comes from a prosperous family and lives in a mansion with her butler, Albert (Jii in Japan), but is frequently seen travelling abroad to fight other mamodo teams. Initially, she states she has no interest in the kingship or in the battle, and that she is only fighting to free her onetime best friend, Koko, from the influence of an evil mamodo named Zofis; later in the series, she is shown to genuinely want to help Brago become king.
Her mother was overbearing and proud and expected Sherry to be perfect as a child, constantly expressing disappointment and disgust with her when she failed. As a result, Sherry grew up very unhappy and ultimately tried to commit suicide by throwing herself into a raging river. She was rescued by Koko, who told her it was important to remain alive to find happiness in the future. The two quickly became best friends.
Koko was constantly bullied because she was poor, though, and when Zofis met her, he used that to his advantage, manipulating her heart to bring those memories to the forefront, turning Koko into a cold person who desired revenge. Using the spellbook, she burned down the town she grew up in, just as Sherry received news that Koko had been accepted into a prestigious university. In utter shock at Koko's actions, Sherry was unable to defend herself from Zofis's attack.
Sherry's life was saved again, this time by Brago, who helped train her to fight, although he hated Sherry's weakness in comparison to his strength. When they fought against Zofis and Koko again, Zofis caused Sherry to believe that Koko had willingly turned against her, causing her determination to falter and hindering her ability to cast spells. While they almost lost, Sherry's belief in her friend prevailed and the two were eventually able to win. After burning Zofis's book and restoring Koko's heart to normal, Sherry vows to make Brago king in gratitude. However, in the end, this vow goes unfinished, as Brago is defeated by Zatch.