ONA
Description
Ami Mizuno is a fourteen-year-old student at Juuban Municipal Junior High School and the second Sailor Guardian to be discovered by Sailor Moon in the Sailor Moon Crystal series. She is the civilian identity of Sailor Mercury, known as the Guardian of Water and Wisdom. Ami is a genius with a rumored IQ of 300, consistently ranking at the top of national mock exams. Her exceptional intelligence, however, initially becomes a source of isolation, as her classmates misinterpret her natural shyness and dedication to study as aloofness or arrogance, leading to a lack of friends before the story begins.

Ami lives with her mother, Dr. Saeko Mizuno, a busy physician in a luxury apartment. She holds her mother in high regard and dreams of becoming a doctor like her. Her father, a painter, lives separately from the family following a divorce, maintaining contact primarily through sending postcards on her birthday. This family dynamic, particularly the absence of her father, is a contributing factor to her early feelings of loneliness. In her civilian life, Ami's hobbies reflect her disciplined nature; she enjoys playing chess, at which she excels, and is an avid swimmer. Despite her studious persona, she also has a private enjoyment of romance novels and, on occasion, demonstrates unexpected skill at arcade games.

Personality-wise, Ami is kind, gentle, and soft-spoken, possessing a well-mannered and polite demeanor. She is the voice of reason within her group of friends and fellow Sailor Guardians, often acting as a calming influence on the more impulsive Usagi. She abhors unnecessary quarrels and is deeply uncomfortable with the idea of harming innocent people. While generally reserved, she has a subtle four-dimensional or quirky side, such as when she first met Luna and thought the talking cat was an angel from heaven. Despite her discomfort with romance, which can manifest as a physical allergy to receiving love letters, she is not immune to pop culture and can become a dedicated fan of idols and entertainment, much to her own embarrassment. Her loyalty to her friends is unwavering, and she is fiercely protective of them, capable of displaying surprising assertiveness when the situation demands it.

In the story of Sailor Moon Crystal, Ami is introduced as a lonely honor student who catches the attention of Usagi Tsukino. Usagi, hoping to get help with her studies, reaches out to Ami, and their genuine friendship becomes the catalyst for Ami's transformation. When Ami is lured into the sinister Crystal Seminar run by the Dark Kingdom, she is brainwashed. However, witnessing Usagi in danger as Sailor Moon awakens her own powers, allowing her to transform into Sailor Mercury for the first time. Her primary motivation stems from the bond she forms with Usagi and the other Sailor Guardians, who are her first true friends. This connection gives her the courage to embrace her destiny as a warrior and gives her something to fight for beyond academic achievement. At one point, she is given the opportunity to study abroad in Germany to pursue her medical dreams but ultimately chooses to stay in Japan, valuing her role as a Guardian and her place beside her friends.

Within the Sailor Guardian team, Ami serves as the de facto strategist and analyst. Her role is not primarily that of a frontline fighter, but rather the "brains" of the operation. She is frequently seen using her Mercury Goggles and a portable supercomputer to analyze enemy weaknesses, scan surroundings for traps, and gather tactical information that is crucial for the team's success. Her strategic mind is so valued that Luna recognizes her as a pillar of the team from the very beginning. Her key relationships are central to her character. Her bond with Usagi is the most significant, as Usagi's unconditional friendliness is what brings Ami out of her shell. She forms a close and trusting friendship with her fellow Inner Guardians, Rei Hino, Makoto Kino, and Minako Aino, sharing in both the burdens of battle and lighthearted, everyday moments with them.

Throughout the series, Ami undergoes notable development. She begins as an isolated individual whose entire identity is tied to her academic success. By becoming Sailor Mercury and forming deep friendships, she learns to value companionship, fun, and her own self-worth beyond her test scores. She grows more confident in her social interactions and becomes more willing to express her opinions, even if it means gently teasing her friends or standing up for what she believes is right. Her evolution is also reflected in her increased combat confidence, transitioning from a purely support-based role to acquiring powerful offensive abilities.

As a Sailor Guardian, Ami possesses a range of notable abilities tied to water in all its forms, including liquid water, ice, and mist. To transform, she uses a transformation pen or brooch, calling out phrases such as Mercury Power, Make Up. Her initial and signature support technique is Mercury Aqua Mist, which creates a dense, chilling fog to blind enemies and obscure their vision. For direct offense, she later acquires powerful attacks like Shine Aqua Illusion, a projectile that can freeze opponents in solid ice, and Mercury Aqua Rhapsody, a more advanced attack performed with a watery harp. Her tactical equipment includes the aforementioned Mercury Goggles, which display data and analytics, and a communication device in her earring. As her power grows, she achieves upgraded forms such as Super Sailor Mercury and eventually Eternal Sailor Mercury, each granting her enhanced strength and new abilities.