1000 years ago was a time of peace and prosperity for humans. It was a time known as the Silver Millennium. The ruler of the universe was Queen Serenity and she ruled from the Moon Kingdom located on, you guessed it, the Moon! From this Moon Kingdom she ruled all of the planets ( Mars, Venus, etc. )
The only real threat at the time was the mirror of this universe known as the Negaverse. This was a universe of deceit, torment, hatred and evil. It was just a really horrible place. Its ruler was an evil woman named Queen Beryl. At the center of this Negaverse was the Negaforce. Her plan was to take over the Universe using this Negaforce to win the battle that would inevitably take place.
Queen Beryl, seizing the opportunity of a Lunar eclipse, led the Negaverse army on an attack upon the Moon Kingdom. The Negaverse won, as the Moon Kingdom's army was no match for the powerful Negaverse army. Four princesses from Planets of the Moon Kingdom attempted to overcome the Negaverse army, but this attempt proved to be futile. The casualties of this war were rather heavy; Amongst them were the Moon Princess, Queen Serenity's only daughter, and The Earth Prince, Darien.
After the initial battle the Negaverse claimed victory. Queen Serenity knew that the Negaverse could not be allowed to rule the universe, so using the Imperium Silver Crystal she sent herself, the Negaverse army, and the Negaforce back into the Negaverse. Before she sacrificed her life, the Queen sent her daughter and all of the planet princesses 1000 years into the future. Now they must seek each other out and fight off the Negaverse's attempts to find the Imperium Silver Crystal so that they may once again use the Negaforce to try and conquer the Universe.