Sailor Moon is the alternate identity of Usagi Tskuino and the leader of the Sailor Senshi. She acts as the reincarnate of Princess Serenity and uses the power of the moon to aid herself. In her civillian form, however, Usagi is just a Tokyo schoolgirl. She was the first Senshi to be found by Luna, who was sent to Earth to awaken the Senshi.
In her civillian persona, Usagi is a schoolgirl who isn't very intelligent. Usagi doesn't take many things seriously and most refer to her as a "crybaby." When Luna first recruits her, she doesn't take it well, reluctantly fighting evil and other monsters. However, as she grows older, befriending and meeting more people, Usagi eventually matures.