The Starlights are three sailor senshi who came to earth in search of their princess, Kakyuu. They lost track of her when fleeing from their destroyed planet, Kinmoku. Kinmoku was destroyed by Sailor Galaxia.

The Starlights disguised themselves as the idol group, The Three Lights. Hidden inside their songs was a subliminal message that only Kakyuu was supposed to hear. Somehow, Usagi felt as if the 3 Lights had a message in their songs. Their hit song was called Nagareboshi he (Shooting Star). They also sang Todokanu Omoi( which was sung in episodes 188 and 195).

The Starlights were not really part of the team in the Sailor Star series. Sailormoon wanted them to fight together as one team of Sailor Senshi, but the outer senshi (minus Saturn) prevent that from happening. Uranus has a particular dislike for them (especially Seiya) but at the end of the series, the outer senshi get over their dislike and entrust their princess (Sailormoon) in the hands of the Starlights.

After the battle with Galaxia, the Starlights return to Kinmoku with Kakyuu. In the manga, the end is completely different. The Starlights are killed by Sailor Phi and Kakyuu is destroyed by Sailor Chi. The Starlights were not mentioned again. Let's hope that they were reborn or sent into the future. ^_^;