Sailor Moon (美少女戦士セーラームーン Bishōjo Senshi Sērā Mūn, originally translated as Pretty Soldier Sailor Moon and later as Pretty Guardian Sailor Moon]) is a Japanese shōjo manga series by Naoko Takeuchi. It was originally serialized in Nakayoshi from 1991 to 1997; the 52 individual chapters were published in 18 tankōbon volumes. The series follows the adventures of a schoolgirl named Usagi Tsukino as she transforms into Sailor Moon to search for a magical artifact, the "Legendary Silver Crystal" (「幻の銀水晶」 Maboroshi no Ginzuishō, lit. "Phantom Silver Crystal"). She leads a diverse group of comrades, the Sailor Soldiers (セーラー戦士 Sērā Senshi) (Sailor Guardians in later editions) as they battle against villains to prevent the theft of the Silver Crystal and the destruction of the Solar System.