Setsuna, Sailor Pluto, is really the first Outer Senshi to be introduced--at the end of Sailormoon R. Of course, we rarely see her, and so know very little about her. She is the guardian of the Time Door and is very dedicated to her job. ChibiUsa and Sailor Pluto have a very friendly relashonship, ChibiUsa in the manga considers Pluto her only friend.
