The eternal guardian of the Door of Space and Time. As early as the era of Queen Serenity, she shouldered the responsibility of the guardian of time and space. She can control time. Her main mission is to guard the Door of Space and Time and prevent others from traveling through time and space at will. Although she is lonely inside, she always fulfills her mission responsibly. Setsuna in the 20th century awakened Sailor Pluto's personality and power in order to prevent Sailor Saturn awakening.