Sailor Moon Dark Mercury

Dark Mercury, portrayed by Chisaki Hama, has a markedly different uniform from her "good" counterpart.

In Pretty Guardian Sailor Moon, Ami is briefly taken over by the power of the Dark Kingdom and becomes Dark Mercury. This form first appears in Act 21, as a servant of Kunzite. Her sailor fuku has black tulle and lace on the back bow and sleeves, and tribal designs appear on her tiara and boots. She also gains a chain with a black charm on it around her waist. Her transformation phrase is Dark Power! Make-up! and is said in a much darker tone. She wields a sword fashioned from an icicle, which she creates herself the first time her transformation is displayed. In promotional photos prior to her premiere, she was shown with a different sword, which seemed to have strings on it like a harp or violin; the latter seems more likely, as she is also seen holding a bow. This bow was redecorated and given to Zoisite for use as a sword.
Dark Mercury is created when Kunzite manages to kidnap Ami in a moment of vulnerability while the other Senshi are busy. He exposes her directly to the power of Queen Metaria, causing drastic personality changes as well as the alterations to her uniform. She is self-confident to the point of egotism, and continues to attend school in civilian form, mainly to antagonize Usagi by brainwashing all of her former friends. Dressing predominantly in black, evil-Ami tends to move about slowly and dramatically, and when confronting the Senshi gives a sense of sadistic glee.
Dark Mercury has no intention of being a follower to anyone, and is always trying to pursue her own agenda, which is to kill her friends and become as strong as possible. She shows blatant disrespect to Kunzite and the other Shitennou, even to Queen Beryl, perhaps because, unlike even the Shitennou, she had been directly exposed to Metaria's power during her conversion, as opposed to having Queen Beryl or another intermediary filtering it.
Despite these alterations, certain aspects of the real Ami still remain. She still wants to do well in school, and wants friends, hence the brainwashing of her classmates. She seems to retain a sense of sympathy, which is evident when she repairs Nephrite's cape for him, stating that she does not like to see him alone.
Periodically, Sailor Moon attempts to heal her friend with the power of the Silver Crystal. Mercury is always snatched away before this can be completed, but it has some effect, ultimately resulting in her recovery. In Act 28, the catalyst for her finally returning to normal is when, having defeated Sailor Moon in battle, the sight of her injured friend causes her to realize she cares about Usagi, and to remember who she really is. After being healed, she has no memories of what happened while she was Dark Mercury. This haunts her, as she becomes terrified of what she may have done to her friends while not in control.

Sailor Moon Aspects and Forms

As a character with different incarnations, special powers, transformations and a long lifetime virtually spanned between the Silver Millennium era and the 30th century, Ami gains multiple aspects and aliases as the series progresses.

First appearance
Form	Manga	Anime	Live-action
Ami Mizuno	Act 2	Ep. 8	Act 1
Sailor Mercury	Act 2	Ep. 8	Act 2
Dark Mercury	--	--	Act 21
Super Sailor Mercury	Act 35	Ep. 143	--
Princess Mercury	Act 41	--	--
Third Senshi form	Act 42	--	--

Sailor Mercury
Ami's Senshi identity is Sailor Mercury. She wears a uniform colored in shades of blue, and is given specific titles throughout the various series. These include Soldier of Water and Intelligence, Soldier of Wisdom, Soldier of Justice and Wisdom, and Soldier of Love and Exams. Her personality is no different from when she is a civilian, although certain powers are unavailable to her in that form.
In Japanese, the name for the planet Mercury is Suisei (水星), the first kanji meaning 'water' and the second indicating a celestial object. Although the Roman planet-name is used, Sailor Mercury's abilities are water-based due to this aspect of Japanese mythology. Initially most of her powers are strategic rather than offensive, and she possesses various pieces of computerized equipment to help her study the enemy.
As she grows stronger, Sailor Mercury gains additional powers, and at key points her uniform changes to reflect this. The first change takes place in Act 35 of the manga, when she obtains the Mercury Crystal and her outfit becomes similar to that of Super Sailor Moon. She is not given a new title. A similar event is divided between episodes 143 and 151 of the anime, and she is given the name Super Sailor Mercury. A third, manga-only form appears in Act 42, unnamed but analogous to Eternal Sailor Moon (sans wings).

Sailor Moon Sailor Mercury Profile

Ami in her school uniform, drawn byNaoko Takeuchi. The "genius" archetype is emphasized in her character design, as seen here in the presence of books and reading glasses.

Ami's most-emphasized character trait is that she is enormously intelligent—in the anime and manga she is rumored by other characters to have an IQ of three hundred, while in the stage musicals this is stated as a fact. She is adept at English in both the musicals and the anime. Her peers view her with a mixture of awe and distaste, misinterpreting her inherent shyness as snobbery, and so she tends to have a difficult time making new friends. Ami is depicted as sweet, gentle, and loyal, as well as slightly insecure. Not to mention she hates it when Sailor Moon and Sailor Mars fight. Anne Allison describes her as "a smart girl who needs to relax", calling her "conscientious" and "studious", "everything Usagi is not". Early on in the story, she relies heavily on the approval of her mother, teachers, and friends, but as the series progresses she becomes stronger and more confident in herself. She is generally the most sensible of the main characters, and is often the only one embarrassed when the group has a dull-witted moment. As the story begins, she attends Azabu Jūban Junior High along with Usagi Tsukino and, later, Makoto Kino.
Throughout the series, much of Ami's free time is spent studying. She loves to read, and dreams aloud of one day being a doctor like her mother and becomes one in both Parallel Sailor Moon and the live action series. In the musicals, Ami's dream of being a doctor and leaving Japan to study abroad is a recurring theme. The first part of the song Dream Yume wa Ookiku (ドリーム　夢は大きく lit. Dream - Dreams are Huge) shows Ami's conflict between studying abroad and growing up or being with everyone else and staying a young girl. She faces a similar dilemma in the anime, but very directly; given the opportunity to study in Germany, she gets as far as the airport before deciding to stay in Japan and fight evil alongside her friends.
Ami has great appreciation for art as well as science, and, contrary to the usual depiction of a bookworm, even enjoys pop culture and romance novels (though she is usually embarrassed to admit it). In both the anime and the manga, Ami's diligence in her studies becomes a running gag; she often comically scolds Usagi and the others for not doing their homework, and she can become obsessive about being the best student. Her character has been interpreted as a political commentary on the education system of Japan. She sometimes displays attraction to boys her age, and other times aversion to the idea. Love letters are listed as the one thing she has most trouble with, and when she later receives one, it gives her a rash. In the anime, a classmate named Ryo Urawa learns her identity and expresses attraction to her, but this is never resolved, as he disappears after just two appearances in the first series.
Besides reading, Ami is shown playing chess and swimming in order to relax. As the team scholar, computers are listed her strong point; she even belongs to the club at school. She loves all her classes, especially mathematics. Her favorite foods are given as sandwiches and anmitsu, with her least favorite being yellowtail. Other loves include cats and the color aquamarine.
Ami is one of the few girls in the series whose family situation is explicitly mentioned in the anime. Her parents are divorced, and she lives with her mother, a busy doctor who is not home very often, named Saeko in the live-action series. They look very similar, and Ami admires her mother and longs to live up to her example. Besides her workaholic tendencies, Dr. Mizuno is portrayed as a good person who openly resents not having more time to spend with her daughter. Ami's father is never named, but is stated in the manga and anime to be a painter. The manga says that he never visits them, having decided one day not to come home from the forest where he was relaxing and painting, but he sends her postcards on her birthday. Thinking about this, Ami sometimes resents her parents' selfishness in separating, partly because divorce in Japan is taboo. However, in the anime Ami seems to appreciate her father and seems to share some of his artistic traits, at one point even composing matching lyrics for a tune that had none. In the manga, Ami's mother is revealed to be fairly rich, as they live in a condominium. Ami is shown testing the strength of a sword that the Sailor Senshi received on the moon by using it to chip a diamond ring. (Classically, a diamond is the hardest mineral.) When the girls panic, she calms them by saying that her mother has many more.
In the live-action series, Ami is especially shy and usually wears glasses while in public, even though she does not need them. At her middle school, she has no friends before meeting Usagi and always eats lunch alone on the roof so she can study. Usagi seems to be the only one to realize that Ami is merely shy, not truly standoffish, and in befriending her gradually helps Ami to learn that she is more than just a bookworm. By Act 34, when Ami's mother attempts to transfer her to another school because she thinks Ami's friends are bad influences, Ami rebels, avoiding the admission interview and spending the night at the Senshi hideout with Rei Hino. Later she tells her mother that what she's doing in her life right now is more important than studying, and her mother understands.
Ami was a kind and gentle person who disliked quarrels and abhorred harming innocent people. This trait was even cited in the title of an anime episode, "Believe in Love! Ami, a Kind Hearted Senshi," 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.