Cleopatra Qubeley serves as a priestess in Regina World, renowned for her exceptional beauty, wisdom, and intelligence. She leads national festivals and is the first to detect unusual disturbances affecting her world. Her inherently frail physical constitution makes her vulnerable, attracting the attention of an unspecified entity. This entity's influence transforms her into Cleopatra Qubeley Dark Mask Ver., placing her under the control of an external will through the Dark Mask. While she previously mastered diverse skills, the Dark Mask significantly amplifies these abilities, granting enhanced powers severe enough to reanimate the deceased.

Within Regina World's Ancient Egypt-themed setting, she partners with Caesar Legend Gundam, a figure based on Julius Caesar. Her possession by the Dark Mask occurs as part of Qiongqi and Sima Yi's broader antagonistic campaign, temporarily aligning her against the series' protagonists. During this period, she acts under the Dark Mask's control, using her augmented abilities to further the antagonists' objectives.

Her liberation from the Dark Mask's influence follows Caesar Legend Gundam's defeat in episodes 18 and 19. After this event, she reverts to her original state, freed from the external will. She has no documented appearances or character development in subsequent spin-offs, movies, or other media.