The Sailor Moon manga series features a cast of characters created by Naoko Takeuchi. The series takes place in Tokyo, Japan, where the Sailor Guardians (セーラー戦士, Sērā Senshi), a group of ten magical girls, are formed to fight against antagonists who aim to take over the Earth, the Solar System and the Milky Way. Each Guardian undergoes a transformation which grants her a uniform in her own theme colors and an elemental power. They are named after the planets of the Solar System, with the exception of Earth but including its moon. While many characters are humans who possess superhuman strength and magical abilities, the cast also includes anthropomorphic animals and extraterrestrial lifeforms.
The series follows the adventures of the titular protagonist, Sailor Moon, her lover Tuxedo Mask, her cat advisor Luna, and her guardians and friends: Sailors Mercury, Mars, Jupiter and Venus. They are later joined by Chibiusa, Sailor Moon and Tuxedo Mask's daughter from the future, and four more guardians: Sailors Uranus, Neptune, Pluto and Saturn. The series' antagonists include the Dark Kingdom, the Black Moon Clan, the Death Busters, the Dead Moon Circus and Shadow Galactica.
Takeuchi's initial concept for the series was Codename: Sailor V, in which Sailor V discovers her magical powers and protects the people of Earth. After the Codename: Sailor V manga was proposed for an anime adaptation, Takeuchi changed her concept to include ten superheroines who defend the galaxy. The manga's anime, live-action, musical and video game adaptations feature original characters the production staff created rather than Takeuchi.