A large palace stands in the center of Tokyo, Japan. The sun glistens off of the glass kingdom and the whole city shines. In the past, this part of the country was constantly under attack. The citizens of Tokyo lived in blissful ignorance however, save for ten certain people. These guardians watched over this city and the rest of the planet and saved it from utter destruction plenty of times. Now, after 100 years and a spell of silence cast over the Earth, these same guardians and their queen have awakened and live in peace, ruling the planet.
1000 years ago there was a similar kingdom ruling not the earth, but the solar system. The kingdom was called The Silver Millennium and it was located on Earth's moon. An evil entity, Metallia, took a woman under her influence. The woman was easily controlled, as she was jealous and highly ambitious. Beryl gathered her own forces and attacked the Silver Millennium on behalf of Metallia.
Metallia was after the Silver Millennium's ultimate weapon, a silver crystal. The source of the Moon Queen's life force and rumored to be one of the strongest weapons in the galaxy. If Metallia could get the crystal in its possession, it could have its own reign over the solar system and expand it even further. Beryl had her own quarrel with the kingdom. Being born on Earth, she had met the Earth's own prince, Endymion, and fallen in love with him. She grew jealous of Endymion's affections for the queen's daughter, Princess Serenity. Metallia saw the opportunity and formed a deadly alliance with Beryl to destroy the Silver Millennium.
Beryl succeeded not only in killing the princess, but the prince and everyone else on the Moon as well. Queen Serenity was the last one left to fight. Each representative warrior from neighboring planets had been killed. Venus, Mercury, Mars, Jupiter, Saturn, Uranus, Neptune, and Pluto; each of them had been defeated. All who remained with Serenity were her two advisors, Luna and Artemis.
Queen Serenity had no choice but to use the Silver Crystal. With all her strength, she unleashed the energy to seal away Metallia, Beryl, and the others. Her court, daughter, and allies were also sealed in the crystal. In order for them not to be destroyed, Serenity had to put them all in a dormant state together.
Though the Silver Crystal is a powerful device, it should only be used sparingly. Repeated uses weaken the holder, and if all the power is used or if it were to break, the user will die. Queen Serenity had expelled most of her energy and lay dying on the remains of her destroyed kingdom. With the last of her strength, she sent the Silver Crystal and the advisors to Earth, her wish being to have them reborn and live peaceful lives, their powers still intact should they need to defend themselves again.
It was only chance that Princess Serenity was reborn in Japan. She became Tsukino Usagi, and at the age of 14, her memories of her past came back, along with the evil of the past as well. As the princess was still dormant, she became Sailor Moon. The Silver Crystal was inside of Usagi's body, which drew the enemies to her and caused her to fight. Five of her inner warriors, Sailor Venus, Mercury, Mars, and Jupiter, joined her and they defeated Queen Beryl and Metallia once and for all. Endymion, now Chiba Mamoru, also regained his memories and reunited with Serenity. After the battle, they lived normal lives until a mysterious child fell from the sky.
The child tracked down Usagi and demanded she give her the Silver Crystal, threatening her when she refused. She identified herself as Tsukino Usagi as well and disappeared, only to show up in Usagi's house, her family under hypnotic influence and insisting that the little girl was part of their family; their young cousin to be exact.
Later, the intentions of the child, nicknamed ChibiUsa, were explained. She was from the future and needed Sailor Moon's help to save her mother. A family from a place called 'The Black Moon" had come and taken control of her land. Sailor Moon, Mamoru, and the Inner Senshi traveled to the 30th Century to see what exactly the problem was. They met Sailor Pluto at the Space Time Corridor and she let them pass to the future.
While in Crystal Tokyo, ChibiUsa's home, they meet Neo King Endymion, Mamoru's future self, and reveals that ChibiUsa is Usagi's daughter. They learn more about the Dark Moon Clan and that the reason ChibiUsa needs the past's Silver Crystal is because the future crystal has gone missing.
They travel back to the 20th century and defeat the Black Moon clan. Usagi became Neo Queen Serenity and revealed the current crystal. The crystal from the 30th Century comes out of ChibiUsa's body and when she realized she had it, ChibiUsa became Neo Princess Serenity and helped her mother destroy the enemy. After the battle, Usagi, Mamoru, and the rest see ChibiUsa off as she goes back to her own time.