Standing in their way are the Sailor Guardians, five middle-school-aged girls - perky Usagi Tsukino, genius Ami Mizuno, paranormally gifted shrine maiden Rei Hino, tomboyish Makoto Kino, and J-pop idol Minako Aino - are sworn to protect the Princess of the Moon and defeat the Dark Kingdom. Two beings that appear to be sentient, stuffed toy cats, Luna and Artemis, serve as the girls' mentors. The Guardians also encounter Tuxedo Mask, a jewel thief in search of an immensely powerful, mystical Silver Crystal belonging to the Princess of the Moon.