Kaioh Michiru - Mature Sea King
Michiru (soon to be Nerissa) is elegant, cultured, and talented.  She excels at nearly everything she
 attempts.  In the anime, she demonstrated her skill at the violin by playing while bouncing
 lemons up and down on it.  (Usagi admired her so much that she tried to play the violin while
 everyone else in the park covered their ears :)
  Michiru is not only beautiful and intelligent and refined, but she is also sweet and polite and ladylike and just about
 every perfect adjective you could think of :).  I think that Takeuchi Naoko said that Michiru is the
 most unlike herself (Naoko that is).
 Prior to meeting the inner senshi and Sailormoon, Sailorneptune and Sailoruranus fought on
 their own as a formidable team.  Sailorneptune wields the power of the ocean, i.e.
 waves, tides, and she can use her talisman as well.
  As Sailorneptune in S, Michiru was colder and decisive because she and Haruka took a very
 serious view of their responsibility to prevent the Silence.  Although they share a close and interdependent
 relationship, they were willing to sacrifice one or the other to complete their mission.
sorry about all of the uncertain knowledge.  i'll verify sometime when i'm not so lazy :)