Though a little clumsy and easily brought to tears, Usagi Tsukino is a typical 14-year-old girl in her second year of junior high. However, all of that changes when an encounter with Luna, a mysterious talking black cat, whose head bears the mark of a crescent moon, results in the animal bestowing a magical brooch upon her. Now Usagi can transform into Sailor Moon, a magical girl in a sailor uniform who protects love and peace! Usagi is appointed as a guardian of justice and is tasked with the search for the legendary Silver Crystal, a magical artifact that holds immense power, as well as finding the other Sailor Guardians and the lost princess of Luna's home, the Moon Kingdom. Her mission isn't without opposition, however; Queen Beryl, ruler of the Dark Kingdom, wants to claim the Silver Crystal and take its power for her own. Though she still has to worry about her school, family, and love life, it is up to Sailor Moon and the other Sailor Guardians to save the day!

The Sailor Guardians and their leader, Sailor Moon, continue their duty of protecting Earth from any who would dare cause it harm. However, Sailor Mars' apocalyptic visions and the appearance of two new guardians—Sailor Neptune and Sailor Uranus—signal that a new battle will soon begin. These newcomers seek three Talismans that are inside the Pure Heart Crystals within human beings. Once brought together, these objects form The Holy Grail, a magical relic with extraordinary abilities. They want to use the Grail to save the world, but an evil organization known as the Death Busters seeks its power for their own desires. The removal of a Talisman from a person's Heart Crystal will cause their death, something that Uranus and Neptune see as a necessary sacrifice to form the Grail, while Sailor Moon and her group deem it unforgivable. But can any sacrifice be worth the cost if it saves the lives of the entire human race?

Usagi Tsukino is an average student and crybaby klutz who constantly scores low on her tests. Unexpectedly, her humdrum life is turned upside down when she saves a cat with a crescent moon on its head from danger. The cat, named Luna, later reveals that their meeting was not an accident: Usagi is destined to become Sailor Moon, a planetary guardian with the power to protect the Earth. Given a special brooch that allows her to transform, she must use her new powers to save the city from evil energy-stealing monsters sent by the malevolent Queen Beryl of the Dark Kingdom. But getting accustomed to her powers and fighting villains are not the only things she has to worry about. She must find the lost princess of the Moon Kingdom, the other Sailor Guardians, and the Legendary Silver Crystal in order to save the planet from destruction.

An unusual snow storm hits Tokyo and the Sailor Senshi discover that an evil snow queen Kaguya, wants to freeze the entire earth. It's up to the Inner Sailor Senshi along with the Outers, to defeat the Queen. Meanwhile, Luna falls in love with a human astronomer named Kakeru whose girlfriend is an astronaut about to take a space shuttle mission. Kakeru becomes ill and Luna wishes she could be a human to help him.