Sailor Neptune, for those of you that don't know, is very wealthy. She, Sailor Uranus, and Sailor Pluto protected the outer solar system during the Silver Millenium. She thought Haruka was cute before she knew she wasn't a guy...she even confronted her about her feelings. Now she and Uranus have this thing going on, and even help to raise Hotaru (Sailor Saturn).
Here is her profile:

Name: Kaioh Michiru (Michelle)
Name Meaning: King of the Ocean
DOB: March 6
Sign: Pisces
Blood Type: O
Fav. subject: Music
Fav. food: sashimi
Fav. color: marine blue
Controls: water
Enjoys: painting, swimming, and violin
Dream: To be a violinist

She is a good artist, as well as a violinist and swimmer. Some of her artwork is even in museums! Once, Sailor Moon wanted to learn how to play the violin so that she could play for Mamoru, but she kind of failed at that. :( Luna thought it was just a passing thing, but it turned out she really wanted to learn. Oh well, everybody isn't made for everything. But apparently Michiru is most definitely in existence to play the violin. ^_-

In the Stars series, Michiru plays with the Three Lights in a joint concert. Seiya and Michiru both sense that there is something special about each other, and want to find out what something is. Haruka and Seiya have a bit of a confrontation too, because he was in Michiru's dressing room afterwards. (No, nothing happened between them...) Michiru sensed that the Three Lights were calling out to someone in their songs. She of course later found out that they are senshi.

Michiru is also a good swimmer, as I said. It shouldn't be as much of a surprise since her power is of water. She and Mercury are pretty evenly matched when it comes to a swimming contest, as well. Her talisman is a mirror, which reflects the truth to her and erases all deception in what it shows.

Love life: Haruka basically constitutes her love life. Seiya tries the enter it for about 30 seconds, but Haruka shows up. Michiru seems to be quite happy with Haruka, so there is really no problem. ^_^

The outer senshi's mission is to protect the princess from invaders from outside of the solar system. This is why they do not like the Starlights, and forbid Usagi to see Seiya. They are very serious about protecting the Earth, and are each willing to sacrifice their own lives if it will save the other guardians. Because no matter what, the princess and the Earth must be protected.