Setsuna Meioh is the civilian identity of Sailor Pluto, Guardian of the Underworld and protector of the Space-Time Door. Her existence spans multiple timelines, originating in the Silver Millennium as Princess Pluto, daughter of Chronos, the god of time. Queen Serenity bound her to guard the Space-Time Door under three strict taboos: never abandoning her post, never permitting time travel, and never disrupting time's flow—violating the last taboo results in death. During the Black Moon conflict, Sailor Pluto encounters Chibiusa after the child enters a forbidden corridor in Crystal Tokyo. They form a close bond, with Pluto serving as guardian and mentor. When the Black Moon clan attacks, Chibiusa steals one of Pluto's Space-Time Keys to flee to the 20th century. Pluto later allows Sailor Moon and her allies passage through the Time Gate to pursue Chibiusa, violating her second taboo. Her ultimate sacrifice occurs when she stops time to prevent Prince Demande's destruction of spacetime, breaking the third taboo and dying. This act breaks Wiseman's control over Chibiusa, enabling her transformation into Sailor Chibimoon. Neo-Queen Serenity subsequently reincarnates Pluto in the 20th century. Reborn as Setsuna Meioh, she initially lacks memories of her past life. She enrolls at K.O. University as a first-year physics student specializing in theoretical physics. Her civilian life includes befriending classmate Reika Nishimura and collaborating on research into spatial distortions around the Sankakusu building. During the Infinity arc, Tellu's Tellun plants trigger her reawakening as Sailor Pluto. Her Garnet Orb resonates with the Talismans of Uranus and Neptune, confirming her role among the Outer Guardians. She joins Haruka (Sailor Uranus) and Michiru (Sailor Neptune) to confront the Death Busters and monitor the potential awakening of Sailor Saturn within Hotaru Tomoe. Pluto's abilities encompass manipulating spacetime, generating rifts for teleportation, and creating energy shields (Garnet Ball). Her attacks include Dead Scream and Chronos Typhoon. She retains her duty to guard the Space-Time Door but increasingly intervenes in battles, aiding the Inner Guardians against Cyprine and participating in the final confrontation at Mugen Academy. When Pharaoh 90 threatens Earth, she collaborates with Uranus and Neptune to erect a planetary barrier. Later, she seals the Tau Star System's wormhole using Dark Dome Close, accepting Sailor Saturn's choice to be sealed alongside the entity. After Hotaru's rebirth as an infant, Pluto, Uranus, and Neptune vow to raise her collectively. In the Dream arc, Pluto works at the Tokyo Bay Astronomical Observatory but loses her transformation abilities due to the Dead Moon Circus's eclipse. She witnesses Hotaru's reemergence as Sailor Saturn and regains her powers when Hotaru restores her Sailor Crystal. By the Stars arc, she serves as a nurse at Juban Public Elementary School, where Hotaru and Chibiusa study. During Sailor Galaxia's invasion, she is killed protecting the school but is later revived after Chaos's defeat. Across media, Pluto evolves from a solitary guardian to an integrated member of the Sailor Guardians. Her relationship with Chibiusa remains constant, marked by warmth and protectiveness. Musical adaptations introduce unrequited love for King Endymion, adding complexity to her loyalty to the royal family. Her design shifts from an initial black-themed manga uniform with a waist chain of Space-Time Keys to a sleeveless leotard in anime, with later upgrades to Super and Eternal forms featuring star motifs and elongated ribbons. Pluto's civilian traits include a preference for dark red, green tea, and physics, with an aversion to eggplant and cockroaches. She enjoys shopping and sewing, aspiring to become a designer. Her zodiac sign is Scorpio, ruled by Pluto, reflecting associations with transformation and the underworld.