Yaten, as (s)he is known, came from Kinmoku, where (s)he served under Princess Kakyuu and lived with Seiya and Taiki. Galaxia attacked, and they fled, Princess Kakyuu disappearing. They came to Earth in search of her, and becoming an idol singing group, the Three Lights, so they'd gain more visibility and hopefully she'd hear of them. Yaten became the keyboardist and was in charge of managing. They attended Juuban in the same class as the Inner Senshi there.
In both the anime and the manga, Yaten is arrogant, cocky, and self-centered, but his/her soft side occasionally shows through. (S)he hates physical activity and would much rather be doing anything but exercise.
In the anime, Yaten is a man who turns into a female Senshi when transforming. He has an interest in photography and becomes friends with Luna. The Starlights are never killed by Galaxia, and return with Kakyuu to their home at the end.
In the manga, according to reports from Naoko Takeuchi's appearance at a San Diego convention, the Three Lights are all females. The Starlights are killed by Animemates. All the Senshi's spirits are sent to their planets and are reborn, so we have to assume the Starlights were, too.
Yaten has long silvery hair, which (s)he wears pulled back into a thin ponytail, with longish pieces hanging out. His/her eyes are a yellowed green. (S)he wears small studs for earrings. (S)he's on the short side. When (s)he isn't in school uniform, (s)he wears men's clothing, especially suits, sometimes unusual colors (what's with the pink?).
As Starhealer, her powers are drawn from Kinmoku. Her fuku is a black leather bikini top, shorts, tall gloves and boots. She has yellow-green strands crisscrossing her neck, with three of the same colored strands around her wrists. Her tiara is a thin gold line with a gold star in the center, with gold stars for earrings.
Yaten is hilarious! (S)he is one of the few mean characters I like. His/her arrogant attitude is amusing, and I love the comments (s)he makes about hating physical activity and all (I can sympathize with that!). Yaten's a really cool person :)