Sailor Starlights

"Penetrating the darkness of night, streaking through the atmosphere, resounding truth, we are three shooting stars!" — Sailor Starlights' introduction

The Sailor Starlights are a group of Sailor Senshi who came to Earth in search of their princess, Kakyuu, after their home planet of Kinmoku was destroyed by Sailor Galaxia.

The Starlights consist of:

Their search for Princess Kakyuu brings them into conflict with the senshi of Earth, specifically with the Outer Senshi, who want the Starlights to leave the planet and leave Usagi alone. The reason the Starlights, specifically Star Fighter, are so interested in Usagi is because Usagi carries the scent of Princess Kakyuu, due to an incense burner that Chibi Chibi possesses.

Manga

The Sailor Starlights are searching for Princess Kakyuu, traveling the galaxy and eventually arriving on Earth to find her. In their civilian forms, they created a band called "Three Lights", and disguised themselves as men; since the band's songs spoke about "finding their princess", this was a tactic to make their identities less obvious, as well as to gain more publicity for the band.

First Anime Series

The Sailor Starlights are essentially the same in the anime as in the manga. One key difference, however, is that their male disguises on Earth are fully biological (i.e. they literally turn into men), and not just cross-dressing. They only become female when they take their Senshi forms.

Sera Myu

Just like in the manga, the Starlights cross-dressed as men but were actually female.

Trivia

Naoko Takeuchi, the creator of the Sailor Moon franchise, specifically decreed that only women could be Sailor Senshi, and wasn't pleased with the fact that the Starlights could change gender in the anime.^[1]
In the manga, each of them can grow a pair of angelic wings, just like Eternal Sailor Moon.
Fans speculate that the Sailor Starlights draw inspiration from the Trimurti, or the three principal gods of Hinduism; Brahma the creator (Sailor Star Maker), Vishnu the preserver (Sailor Star Healer) and Shiva the destroyer (Sailor Star Fighter).