Ami Mizuno excels academically as a teenage girl, consistently topping national exams and sparking rumors of a 300 IQ. Her natural shyness and intense focus on studies lead peers to misinterpret her as aloof or snobbish, resulting in social isolation prior to her friendship with Usagi Tsukino. She resides with her mother, the busy and respected doctor Saeko Mizuno, following her parents' divorce. Contact with her painter father remains limited, confined mostly to annual birthday cards. Aspiring to become a physician like her mother, Ami dedicates significant time to her studies. Her hobbies include swimming, chess, reading, and video games, alongside a secretly enjoyed but embarrassing fondness for romance novels and pop culture. Personality-wise, Ami is gentle, kind, loyal, and initially insecure, heavily reliant on external validation from authority figures and friends. Her interactions with Usagi and the Sailor Guardians gradually foster greater self-confidence and assertiveness. She remains the team's most level-headed member, frequently serving as their strategist. Her calm demeanor and analytical approach are balanced by a strong moral compass; she dislikes conflict and vehemently opposes harming innocents. Despite her typically reserved nature, she demonstrates firmness when necessary, such as intervening to halt hysterical reactions during crises. As Sailor Mercury, Guardian of Water and Intelligence, she fights for "Love and Intelligence." Her powers stem from the planet Mercury, known in Japanese as "Suisei" (水星), linking her abilities to water and ice. Initial capabilities focus on support and analysis: she generates obscuring mist or fog (Mercury Aqua Mist/Shabon Spray) and employs a magitek visor summoned via her earrings to scan enemies for weaknesses, using a communicator earpiece for team coordination. Her offensive powers evolve significantly: - Early attacks include Shine Aqua Illusion, a water-based blast capable of freezing targets. - During the Black Moon arc, she gains enhanced hydrokinetic and cryokinetic powers from Neo-Queen Serenity's "planet power," though initially overpowered and captured by Berthier due to shared water-based abilities. After rescue, she utilizes new techniques like Shine Snow Illusion, creating blizzards against adversaries. - In the Infinity arc (Season III of *Sailor Moon Crystal*), her upgraded "Mercury Aqua Mirage" attack engulfs enemies in freezing water. She continues tactical analysis with her visor, identifying weaknesses in foes like Mugen Academy Daimons, while noting yet failing to identify suspicious observers during battles. - Her ultimate power, Mercury Aqua Rhapsody, manifests after obtaining the Mercury Crystal in the Dream arc, summoning a harp to channel potent water-based energy blasts. Her transformations reflect power progression: - "Mercury Power, Make Up!" facilitates her base form. - "Mercury Star Power, Make Up!" incorporates her Star Power Stick. - "Mercury Planet Power, Make Up!" utilizes Neo-Queen Serenity’s upgrade. - "Mercury Crystal Power, Make Up!" activates her Super and Eternal forms via the Mercury Crystal. Her Eternal Sailor Mercury form, achieved in the Stars arc, features a redesigned uniform with a star-shaped brooch, V-shaped choker, translucent sleeves, elongated gloves, layered skirt, and knee-high white boots. In the manga and *Crystal* continuity, she is revealed as Princess Mercury of the Silver Millennium, residing in Mariner Castle and tasked with protecting Princess Serenity. This past-life identity resurfaces when she and the other Guardians assume princess forms to amplify Sailor Moon’s power into her Eternal form. Her story includes periods of vulnerability: brainwashing by the Dark Kingdom during her introduction, captivity under the Black Moon Clan, and the temporary theft of her Sailor Crystal by Sailor Aluminum Seiren in the Stars arc. Each time, her resilience and loyalty to Sailor Moon and the team enable her recovery and continued service as a Guardian into the Crystal Tokyo era.