Princess Mercury is the royal, pre-incarnation form associated with Ami Mizuno in Bishoujo Senshi Sailor Moon. She is one of the four guardians of Princess Serenity and serves as the Moon Kingdom’s embodiment of wisdom and intelligence. In the series’ backstory, she represents Mercury’s calm, strategic, and analytical nature. Her role is tied to the Silver Millennium’s royal court, and her presence reinforces Ami’s character as a brilliant tactician and loyal protector.