Princess Kakyuu came from Kinmokusei, where Yaten, Taiki, and Seiya served under her. Galaxia attacked the planet and she disappeared. The Starlights came to Earth in search of her.
In both the anime and the manga, Kakyuu rarely appears, so not much is known about her or her personality. She does seem to be very compassionate and is glad to see her friends again.
In the anime, Galaxia kills her by taking out her Star Seed. She is reawakened and returns home with the Starlights at the end.
In the manga, she becomes a Senshi, Sailorkakyuu. She is killed by Sailor Chi, one of the Animemates. All the Senshi's spirits are sent to their planets and are reborn, so we have to assume she was, too.
Kakyuu has long red hair which she wears in an ornate style; a loop on either side in the back, a piece framing each side of her face, plus a long piece coming out on the sides, with some gold flower adornments and a black hat of sorts. Her eyes are red. I'm not sure how tall she is compared to the others, and I've never seen a picture where you can see her ears. She only appears wearing a fancy red dress with black trim and some turquoise/blue and gold sections, with upturned shoes.
As Sailorkakyuu, her powers are drawn from Kinmokusei, with assistance from the Starlights. Her fuku is an unusual one (I'll have to guess on the colors...); a red collar; red bikini top with the same adornment as the Starlights; puffed, shoulder-baring sleeves; a slightly transparent petal-like red skirt; plus those funky shoes and hat, and a tiara like the Starlights'.
Well, I've only seen her in episode 200 and in manga 18, so I really don't know what to think of her. She seems ok... I was a bit mad when Chi killed her, cuz she doesn't seem like the type to fight. As for the anime... no clue. Ah well, she's got a neat outfit... And, um... there you go.
Senshi Name: Sailorkakyuu