Dark Mercury

Dark Mercury, who has also been referred to by the unofficial nicknames of Darkury or Dark Sailor Mercury outside of the series, was the evil form of Sailor Mercury who appeared only in Pretty Guardian Sailor Moon. She first appeared in Act 21, after Sailor Mercury was kidnapped and brainwashed by Kunzite.

At first, she appeared like a normal, but cooler Ami (dubbed "Akumi" - meaning "evil beauty" in Japanese kanji characters - by the series production staff). But shortly thereafter she transformed into Dark Mercury, much to the horror of the other Sailor Senshi.

She was often disrespectful toward Kunzite and the other Shitennou, and even to Queen Beryl. She could, however, show kindness, such as when she repaired Nephrite's cape. (After this incident, Nephrite acted strangely in front of her, a possible hint that he might have had some feelings for Ami.)

Dark Mercury returned to normal in Act 28, after realizing that she had hurt Sailor Moon. After that, Ami had no memories of what she did as Dark Mercury.

Transformations

 * Dark Power, Make Up - Used her Dark Jewelry Star Bracelet to transform into Dark Mercury.

Attacks

 * Dark Sword - Dark Mercury transformed an icicle into a sword and used it to fight.

Costume
Dark Mercury's sailor fuku had several unusual design elements. Her choker, collar, skirt, glove fittings, and boots were a slightly darker shade of blue than her usual costume, while her front bow was replaced by a dark blue butterfly-like design, trimmed in black. Her choker, collar, and boots were decorated with a black pattern. Her back bow was black and made of a netting-like material. Her sleeves were made of the same lacy material as her back bow, and the same material also could be seen behind her front bow. A black heart-shaped pendant hung from her choker, matching the one depending from the black belt around her waist. Her earrings were heart-shaped and black. Her tiara was silver with a black pattern, with a blue gem in the center. She also wore her Dark Jewelry Star Bracelet on her left wrist. Her transformed hairstyle also had black shading in some areas in addition to the standard blue.

Trivia

 * Dark Mercury was shown holding a harp-like bow in promotional images and even in an initial DVD cover design, but it was never actually used in the series (as she instead used the Dark Sword). The bow design was modified and became a dagger used by Zoisite.
 * The nickname "Akumi" (悪美) is a combination of the kanji "aku" (悪; meaning "evil") and "mi" (美; meaning "beauty"). The name is a play on Ami's real name (亜美), being similar in both kanji and pronunciation.
 * According to the "Oshiokiyo" omake on the DVD, Dark Mercury was dubbed "Darkury" on the set. The name, which was never used in the series, was quickly adopted by fans and has become a very common nickname for the character.