Ami Mizuno is a highly intelligent teenage girl whose academic excellence, placing her at the top of national exams, initially caused peers to mistake her shyness for aloofness before becoming a Sailor Guardian. Her parents are divorced; she lives with her mother, Saeko Mizuno, a doctor with a demanding schedule, while her artist father maintains limited contact through occasional postcards, contributing to her early feelings of loneliness and self-reliance. In her civilian life, she contrasts sharply with her identity as Sailor Mercury, the Guardian of Water and Wisdom, activated by Luna as the second Sailor Guardian to join Sailor Moon. Her powers, derived from Mercury's association with water ("Suisei"), evolve from supportive abilities like Shabon Spray, which creates a concealing fog, to offensive techniques such as Shine Aqua Illusion and Mercury Aqua Rhapsody. Her role as the team's strategist is solidified by her analytical skills, aided by a handheld computer and a visor summoned through her earrings. Her personality transforms from timid and insecure to confident and assertive across the series. Early on, she relies heavily on others' approval, but through battles and camaraderie—especially her deep friendship with Usagi Tsukino—she grows into a resilient warrior capable of openly challenging enemies and mediating team conflicts. She retains core traits of gentleness, loyalty, and a dislike for confrontation. Secretly, she enjoys romance novels and pop culture, often hiding these interests out of embarrassment. Key arcs demonstrate her growth: - During the Dark Kingdom arc, she sacrifices herself fighting the DD Girls to save allies, later revived by the Silver Crystal. - In the Black Moon arc, she is captured by Berthier but rescued, highlighting her vulnerability and the team's interdependence. - The Infinity arc sees her power upgraded to "Super Sailor Mercury" by Neo-Queen Serenity, enhancing her abilities and modifying her uniform with a heart-shaped gem and star-adorned choker. - In Sailor Moon Eternal (adapting the Dream arc), she gains the Mercury Crystal, enabling direct transformation into Super Sailor Mercury and access to the Mercury Harp. This arc culminates in her assuming the "Princess Mercury" form with other Guardians to empower Eternal Sailor Moon, reaffirming her loyalty to the Moon Kingdom legacy. - The Stars arc introduces her "Eternal" form, featuring star-shaped accessories and elongated gloves, before her Sailor Crystal is stolen by Sailor Aluminum Seiren. After Chaos's defeat, she is resurrected and returns to civilian life. Her aspiration to become a doctor like her mother creates narrative tension, notably when she nearly accepts a study-abroad opportunity in Germany but chooses to remain with the Guardians. Romantic subplots include a brief, unresolved connection with Ryo Urawa, a psychic classmate. In the future of Crystal Tokyo, she serves as a trusted guardian to Neo-Queen Serenity and Princess Chibiusa. Her legacy endures through her duality: a genius striving for academic excellence and a compassionate warrior whose intellect and elemental powers protect the Solar System.