The Sailor Moon anime series was co-produced by TV Asahi, Toei Agency and Toei Animation. It is based on the manga series of the same name, and in fact started airing only a month after the first issue of the manga was published. It is the best-known component of the Sailor Moon franchise. The story of the various metaseries revolves around the reincarnated defenders of a kingdom that once spanned the solar system, and the evil forces that they battle. The major characters—called Sailor Senshi (literally "Sailor Soldiers"; frequently called "Sailor Scouts" in the North American version)—are teenage girls who 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 sera fuku ("sailor outfit"), after which the Senshi's uniforms are modeled. Fantastical elements in the series are heavily symbolic and often based on mythology.