Kou Taiki was one of the three members composing the idol group called the Three Lights, and the civilian form of Sailor Star Maker.
Along with Kou Seiya and Kou Yaten, Sailor Star Fighter and Sailor Star Healer respectively, Taiki came to Earth from the planet Kinmoku in search of their princess. They took on male forms because they felt it would be easier for popular men to attract the attention of women. (In the anime Taiki physically transformed to become male in civilian form, but in the manga she only dressed like a man.)
Some fans have speculated that the Sailor Starlights' names might be derived from the Hindu Trimurti: the Creator, the Preserver, and the Destroyer.