Setsuna is a very blunt and logical girl, and therefore she often seems cold and insensitive. Setsuna likes to shroud herself in mystery. She also seems to have trouble consoling children. The reason of this is she does not wish to become involved in the time-stream, but when she does appear, all heck will probably break loose very soon.
As Sailor Pluto, she is the guardian of time. Sailor Pluto was never reincarnated, and therefore she is really very, very old, and very little is known about her past. However, with age comes wisdom. Sailor Pluto is the only one who has seen everything from the past and to the future. She is probably one of the most powerful of the senshi, since she has to take the important responsibility of guarding the gate of time (which exists out of time and that is why she never gets old).
Sailor Pluto's duty is to correct time distortions, and she has the ability to stop time though she is forbidden to do so, as told by Neo Queen Serenity before her deep sleep inside the palace.It is from her that the other senshi discover the Holy Grail and that only it can help them save the world.
Her heart crystal is in fact the third talisman;
The Garnet Orb. It is adorned on the top part of her staff, which makes the staff look like a key (and it is a time key).
Along with Uranus' and Neptune's talismans, the three combines to form the Holy Grail, which enabled Sailor Moon to transform into Super Sailor Moon.
