Ami is the reincarnation of the Princess of Mercury, and as such holds the power to transform into Sailor Mercury, the Soldier of Water. She was the first of the Senshi to be awakened by Luna after meeting Usagi (apart from Venus, who was awakend by Artemis a year before) and so has known her the longest.

Ami is extremely gifted academically, with her grades always among the best in the country. She transferred to Usagi's school, Juuban Junior High from an elite school, and originally found it difficult to make friends. She often helps the rest of the inner Senshi with schoolwork and is almost like a teather within the study group they have at Rei's place. Although very intelligent naturally, she needs to study a lot herself to maintain her near-perfect results. She also attends evening 'cram school' lessons and keeps herself very busy.

Luna also gave Ami a small supercomputer and VR visor, which she used to analyse people and substances, make calculations, find escape routes and generally do things that are impossible with the normal eye.

Ami is very much the brains of the Senshi's operation, although this in no way weakens her ability as a soldier, and she is an integral member of the group. Early in the series, her Shabon Spray attack frequently confused the enemy by limiting their visibility.

Although very shy, she gradually comes out of her shell a little as the series progresses, and is always very kind and helpful to everyone she meets. She has a special relationship with Urawa Ryu (Greg in the English dub) and although he only appears in 2 episodes, some people would say he was her boyfriend.

Ami loves chess and swimming, and lives with her mother, who is a Doctor. Ami's aspiration is to be a Doctor like her mother, and they hold a deep affection for each other, even though they generally don't see so much of one another due to her mum's work.