, better known as , is a fictional superheroine who is also the
protagonist and
titular character in the
Sailor Moon manga series written by
Naoko Takeuchi. She is introduced in chapter #1, "Usagi - Sailor Moon", originally published in Japan's
Nakayoshi on December 28, 1991, as a carefree schoolgirl who can transform into Sailor Moon, the
de facto leader of the Sailor Soldiers. She is initially believed to be an Earthling, but is later revealed to be the princess of the moon kingdom Silver Millennium. She later discovers her birth name, .