Ami Mizuno was the present incarnation of Sailor Mercury, and appeared in all versions of Sailor Moon.
Ami was a shy girl who did not make friends easily, preferring to be alone with her books instead. Her classmates mistook her withdrawn nature for arrogance, so they did not approach her either until Usagi started doing so. She studied very hard and regularly finished at the top of national exams, leading her classmates to speculate that she was superhuman and had an IQ of 300. Math and science were her favorite subjects, and she was aiming to become a doctor like her mother. Usually calm and level-headed, she was the voice of reason of the Senshi team. The others often relied on her plans and analyses, but they often thought she should "loosen up" more.
Ami was a kind and gentle person who disliked quarrels and abhorred harming innocent people. This trait was even cited in the title of anime episode 122, where she persuaded Sailor Uranus and Sailor Neptune not to kill Hotaru. Like her comrades, her loyalty to Sailor Moon was unwavering, and she would sacrifice her life for her princess if necessary.
In Pretty Guardian Sailor Moon, Ami was far less innocent and trusting, and was a more conflicted character. In this continuity, her desire to become a doctor was actually due to pressure by her mother, and it would take a while for them to reach an agreement. At one point in the series, she was kidnapped and brainwashed by Kunzite; her evil identity was referred to as "Akumi."
Ami lived with her mother in all continuities, although they were not particularly close due to her mother's busy schedule as a doctor. Ami's father, a painter, was divorced from her mother. He sent Ami a birthday card every year, but she had not seen him for a long time.
In the story "Parallel Sailor Moon," she was married to an unseen man and had one child, also called Ami. Ami worked as an underpaid doctor alongside her husband, and her daughter was also a Sailor Senshi.
Ami spent most of her time studying and fighting as Sailor Mercury, leaving little for hobbies. However, she enjoyed swimming and playing chess, both of which she excelled at. She also liked listening to music.
In the anime, Ami also acquired other hobbies and talents, including songwriting and fixing cars.
In the first season of the anime, Ami and Ryo Urawa developed feelings for each other, but Ami denied them at first, saying she had no time for a boyfriend. The two eventually went out on a date, but Ryo left Tokyo soon after, and though he appeared in the penultimate episode of the first season as a non-speaking illusion, he was never mentioned in the series again. In the video game Sailor Moon: Another Story, he returned for the holidays, but was attacked by Youma. He gave Ami a prophecy he learned in a vision, then disappeared shortly after and was not seen again.
In Sailor Moon Sailor Stars, Ami initially seemed to be attracted to Three Lights keyboard player Kou Taiki, who was also very intelligent and a studious type like herself. However, Ami's idealism and her faith in Sailor Moon clashed with Taiki's cold reasoning and dislike of the Senshi. At one point, when Ami (as Sailor Mercury) was losing a battle against a monster, Taiki actually left instead of helping her. They interacted quite a lot during the season, but there was no romance, even implied, between them.
In the Senshi/Shitennou pairing picture drawn by Naoko Takeuchi, Ami was shown together with Zoisite. The only canon occurrence of this pairing was in the musicals, and both the songs "Itsuwari no Forevermore" and "Koi no Dangerous" dealt with their relationship. The pairing has also appeared in numerous fanfictions. In the live-action series, she seemed to feel pity for Nephrite when she was Dark Mercury, and she gave him a new cape. After Nephrite's rebirth as a human, he tried to find a gift to repay her.
- In Act Zero of the live-action series, before she discovered her identity as Sailor Mercury, Ami imagined herself as "Sailor A," wearing the same costume of Sailor V.
- In the side story "Ami-chan's First Love" and the anime short based on it, it was revealed that Ami was allergic to love letters and would break out in a rash when she received them.
- Ami's membership number in the Three Lights Fan Club was 25, making her the first one among her Senshi friends to join the club.
- She was one of only two Solar System Senshi whose given name was written with kanji, the other one being Minako Aino.
- In both the live-action series and the Ami's First Love special, she was sometimes shown wearing glasses. She said she did not need them though, and only wore them for the looks.
- In Act 15 of the manga, Ami demonstrated the ability to sense water even when in civilian form.