The Princess of Estoa is a minor character from the live-action series Pretty Guardian Sailor Moon, appearing only in Act 10. She is the princess of Estoa, a fictional country whose location on Earth is never disclosed; the series provides no details about the country beyond its name and the fact that it has a royal family. The character is identified only by her title, and her given name, age, and personal history are not established.

As a human civilian, the Princess of Estoa has no special powers or abilities and does not take part in combat. Her role in the story is brief and centered on a single incident. During Act 10, the Dark Kingdom general Zoisite uses his Requiem in an attempt to destroy all princesses. The Princess of Estoa is caught up in this attack and falls gravely ill as a result. She is saved by the power of Sailor Moon, who restores her health, and she survives the ordeal.

Because she appears only once and has no developed dialogue or arc, her personality and personal motivations are not explored in the series. She functions primarily as a plot device that shows the wide-reaching danger of Zoisite's scheme and demonstrates Sailor Moon's ability to heal and protect others. Her key relationships are likewise limited: she is tied to Zoisite as a target of his attack, and to Sailor Moon as her rescuer. No other connections, such as family members or attendants, are shown despite her royal status. The character undergoes no meaningful development, as her story begins and ends within the same act, concluding with her recovery.