The Sailor Scouts are a number of super heroine who protect the earth from the dark forces. Each of the Sailor Scouts are named after the different planets and each are associated with a particular element. The Sailor Scouts are divided into two main groups, the Inner Sailor Scouts and the Outer Sailor Scouts. Each of the Sailor scouts were princess of their own home planet and served the Moon Princess Princess Serenity.

Setsuna Meio (Trista Meioh in the English dub) is Sailor Pluto, and she guards the gates of time. Sailor Pluto's first appearance is during Sailor Moon R, where she watches over Chibi-Usa in the past, with whom she has a very special relationship. She is the keeper of the Garnet Orb.

Setsuna is the oldest of the nine Sailor Senshi (she is a college student while the others are still in middle or high school), yet never assumes any type of official leadership role. Even among the Outer Senshi, she frequently defers to Uranus and Neptune. Her name means 'Moment, Dead King'.