She was called the Golden Queen, Galaxia.
The metal-suited Sailor Senshi traveled the galaxy from one end to the other, leaving a wake of chaos, death, and destruction, behind her. She traveled from world to world, stealing the starseeds of the Sailor Senshi who protected their planets with their last dying breath. Some chose to join her, and they pledged their starseed and their souls in return for prolonged life. She granted power to these forsaken guardians, and they in turn joined her growing army. These Senshi without starseeds, kept alive by a pair of golden bracelets bestowed by Galaxia, were known as the Sailor Animamates.
Galaxia and her Animamates continued to collect the galaxy's starseeds, destroying all that opposed them. But one starseed managed to escape Galaxia's grasp, even as the Golden Senshi destroyed the planet that it belonged to. The ruler of the planet Kinmoku, the wise and regal Princess Kakyuu, fled from her dying world to seek refuge from Galaxia's minions.
Kakyuu managed to reach a small, rural planet on the edge of the galaxy that was protected by Sailor Senshi of legendary strength. Finding safety on that planet - Earth, the third planet of the Sol system - Kakyuu remained in hiding while she nursed her wounds and replenished her power.
But Princess Kakyuu was not alone.
Three proud and noble Sailor Senshi also managed to escape Kinmoku, and followed their princess to Earth. Unable to locate her whereabouts, the three Sailor Senshi adopted civilian identities and settled in for a long visit.
Their names were Seiya Kou, Taiki Kou, and Yaten Kou. Also known as Sailor Starfighter, Sailor Starmaker, and Sailor Starhealer (respectively), the three were collectively referred to as the Sailor Starlights. Because each was musically inclined, they decided that the best way to contact their missing princess would be through the power of song. Forming a musical trio, the Three Lights, the three quickly gained fame and fortune as their songs rose to the tops of the charts. Although female in Sailor Senshi form, the Three Lights posed as males while in their civilian forms, having decided that this was the best way to attract attention to their music.
The trouble began when Galaxia turned her attention toward the Earth. Galaxia dispatched the Sailor Animamates to search for the starseeds that the rural planet harbored. Among them was supposedly the starseed with the most brilliant shine in the galaxy... that of the Moon Princess, Serenity.
When the Animamates arrived on Earth, the Sailor Starlights were once again called to battle. However, instead of facing the menace alone, they were joined in their battle by the Sailor Senshi that guarded Earth - Sailor Moon, Sailor Mercury, Sailor Mars, Sailor Jupiter, and Sailor Venus.
The two teams of Sailor Senshi learned to work together, even if there was some opposition from the cynical Senshi of the outer solar system - Sailor Uranus, Sailor Neptune, Sailor Pluto, and Sailor Saturn.
At the same time, the Three Lights settled into life as "normal" Earthlings. They even made friends, such as Tsukino Usagi and her companions. But as time dragged on and there was still no sign of Princess Kakyuu, the Three Lights fell into despair. Where was their Princess? Had she forsaken them? Could they find her before Galaxia descended to Earth and destroyed the planet?