[SENSHI] Sailor Mercury.
Luna mistook Ami Mizuno for the enemy, but then a youma attacked her in her cram school class. Luna gave Ami a Henshin Pen, and she turned into Sailor Mercury. Sailor Moon finally had an ally after fighting alone.
The new senshi was an asset to the team due to her high IQ and ability to strategize. Unlike the other senshi, Mercury did not have any offensive attacks at first. Her basic power Shabon Spray was purely defensive, and it was unable to physically harm anyone. However, it did prove useful when used. Without it, an opponent’s vision would not have been impaired, and the other senshi couldn’t have attacked as easily. Both Sailor Mercury and Sailor Neptune command water, but the latter senshi had dominion over sea water and lacked Mercury’s freezing capability.
Sailor Mercury had some important achievements in the first season of the anime. Where Jupiter failed to beat the evil Endymion alone in episode 41, Mercury was able to trick him and free his prisoners within the Black Crystal. In episode 45, a group of youma were getting the best of the Sailor Senshi. One produced illusions that were a major deterrent to success. Mercury knew she was the weakest, attack wise, and sent Moon off with Mars and Venus. Alone and in her final moments, Mercury broke the illusion conjuring device.
Mercury’s abilities advanced in R twice - she had two new defensive powers: Shabon Spray Freezing and Shine Aqua Illusion. Both gave her control over water and ice. In SuperS, Pegasus upgraded Mercury to her super form. She was able to use Mercury Aqua Rhapsody, her strongest attack yet.
In the last season of the anime, Sailor Mercury was teamed up with Uranus during the Nehelenia storyline. Uranus questioned Mercury’s fighting methods, which involved a less physical approach. With proper analysis from her supercomputer and Mercury Goggle, Mercury gave Uranus the necessary information to defeat Nehelenia’s minion. When Galaxia’s assault heightened near the end of the series, Mercury and the other Inner Senshi sacrificed themselves to protect Sailor Moon and the Starlights. Mercury’s star seed was taken, and she eventually died like the others. Sailor Star Healer was in disbelief over the girls’ actions. Mercury told the Starlights that it was because they were important like Usagi. Eventually, Mercury was revived once the battle was won and her star seed was returned.
Sailor Mercury’s sentofuku (combat uniform) was similar to Sailor Moon’s early one. Her solid choker, pleated skirt, knee high boots and sailor collar were all blue. The collar had two stripes like Sailor Moon’s, and the boots had the same white edging. Mercury’s chest and back bows were light blue, and the front one was topped with a plain blue, circular brooch. Around the top of her elbow length gloves were three blue rings. Her shoulder pads connected to the bust section, and the skirt and back bow attached to a white, padded hip roll at the waist. Mercury’s simple ear studs were blue, and so was the jewel in her tiara.
In SuperS, Ami was given a Crystal Change Rod. With it, she became Super Sailor Mercury. The main differences to her costume were a longer back bow, a blue heart shaped chest brooch, one translucent sleeve on each shoulder pad, a gold star on the choker, and three studs per ear.