Sailor Neptune (セーラーネプチューン, Sērā Nepuchūn?) is one of the central characters in the Sailor Moon metaseries. Her real name is Michiru Kaioh (海王 みちる, Kaiō Michiru?, or Michelle in the English anime), an artistic schoolgirl who can transform into one of the series' specialized heroines, the Sailor Senshi.

Introduced in the third story arc, Sailor Neptune fights alongside her partner and lover Sailor Uranus in defending the Solar System from outside threats. In both versions of the story, she is elegant, sophisticated, capable of sharp anger, and sometimes cold. She is fully dedicated to her duty as a Senshi.

Source: Wikipedia