Sailor Moon is a media franchise created by mangaka Naoko Takeuchi. The story revolves around the reborn defenders of a kingdom that once spanned the solar system, and the evil forces that they battle. The major characters—the Sailor Senshi (literally "Sailor Soldiers"; frequently called "Sailor Scouts"), teenage girls—can transform into heroines named for the moon and planets (Sailor Moon, Sailor Mercury, Sailor Mars, etc.). The use of "Sailor" comes from a style of girls' school uniform popular in Japan, the sērā fuku ("sailor outfit"). The elements of fantasy in the series are heavily symbolic and often based on mythology.