Long, long ago, about a thousand years ago to be exact, there lived a Queen called Queen Selenity on the Moon. Mysteriously, she gave birth to a daughter- without the aid of a male counterpart. This daughter was named Serena. She lived on the Moon with her sister, Princess Mina of Venus, and their four bodyguards, Princess Amy of Mercury, Princess Rei of Mars, Princess Lita of Jupiter, and Princess Jenny of Saturn. They all lived happily together- or so it seemed.
Princess Mina, utterly sorrowful at being the "less important" of the Moon sisters, went insane. To ease her grief caused by the the insanity of her daughter, Queen Selenity began to date Princess Serena's fiancee, Prince Endymion. She eventually had a daughter with him, named Chibi Chibi (alternate sources say that Chibi-chibi was the daughter of Princess Rei and Prince Endymion). To cover up her birth, they pretended they didn't know where she came from and sent her away to go live with Endymion's cousin, Sailor Galaxia. To add to the circulating rumors, a palace staffer was sure he once saw Princess Jenny consorting with Satan. There were also many contreversies about Princess Amy and all those men she invited to her room . . .
And from there things got worse. Queen Metallia, Queen Selenity's evil twin sister, attacked the Moon with her powerful Netherforce. Even Princess Rei in Eva 00 and Princess Jenny with her Silence Staff could not stop Metallia. One by one the senshi fell, until no one stood in her way. No one except Princess Serena, Queen Selenity, Prince Endymion, and the royal cat family (Diana, Luna, Atremis).
When Metallia reached the Moon palace, she tried to persuade Endymion to join sides with her. He refused, so she killed Serena and took him away to the Netherworld. There she brainwashed him into thinking that he was an evil girl named Princess Darine.
Queen Selenity, greatly saddened by this course of events, asked Sailor Pluto to send the Sailor Senshi into the future. Sailor Pluto said that if she did, it would cost Queen Selenity her life. The Queen agreed to that, and pretended to use a silvery-colored crystal that Sailor Fireball had once given her as a book-end to do the job while Pluto worked. She silently prayed as she died that her daughters would never think that the crystal had any real power, since it didn't....