Ami was the first senshi to be found, after Usagi. She was a new girl at Juuban and was thought to be a possible member of the Dark Kingdom. She was attending a cram school run by the Dark Kingdom and was attacked by the teacher, who was actually a youma. The sign of Mercury appeared on her forehead and Luna gave her a henshin stick. Ami is often referred to as the brains of the senshi, due to the fact that she has a mini-computer she can use to analyze things and a visor which can scan enemies. Her IQ is somewhere around 300 and she wants to become a doctor. Her mother is a doctor and her father is a painter.

Personality wise, Ami can be described as quiet or shy. Sometimes she can make comments which shocks everyone due to the fact that she is usually softspoken. She spends more of her time studying, especially in S when the high-school entry exams are coming up. In Stars she loosens up and chases after the Three Lights with the other girls.

In the first season she has a somewhat boyfriend Urawa Ryo. In the special "Ami's First Love" she receives a love letter from an unidentified source, which causes some problems, since she is allergic to love letters.