Setsuna Meiou is the civilian identity of Sailor Pluto, Guardian of Space and Time, bound by oath to protect the Door of Space and Time under immutable laws forbidding desertion of her post, unsanctioned time travel, or freezing time—a violation punishable by death. Originating in the Silver Millennium, she was appointed by Queen Serenity to stand eternal vigil at the door, enduring solitude to preserve temporal balance. In the Black Moon conflict, her bond with Chibiusa proves instrumental in freeing the latter from corruption as Black Lady. Her choice to halt time to save allies results in her demise, but Neo-Queen Serenity reincarnates her in the 20th century as a physics student devoid of her past memories, granting her a fleeting mortal life. During the Infinity arc, Setsuna’s dormant guardianship reawakens upon meeting Haruka Tenoh and Michiru Kaioh, reclaiming her mantle as Sailor Pluto to confront the Death Busters. Her Garnet Rod and Orb unite with Uranus’ Sword and Neptune’s Mirror to summon the Holy Grail. She aids Haruka and Michiru in nurturing Hotaru Tomoe, the reborn host of Sailor Saturn, while navigating her dual role as both enforcer of cosmic order and ally to the Outer Guardians. The Dream arc reveals her adaptability as she assumes the guise of a school nurse to protect Chibiusa, blending nurturing care with strategic vigilance. Though initially hindered by her reincarnated form’s limitations, she eventually regains her full power as Eternal Sailor Pluto, her upgraded uniform symbolizing newfound freedom to traverse timelines unrestrained. In the Stars arc, Sailor Galaxia annihilates her, but Chaos’s defeat allows her resurrection alongside fellow Guardians. Spin-off media, such as musicals, expand her narrative, portraying her concealed loneliness and quiet affection for King Endymion, layering vulnerability beneath her stoic exterior. These adaptations also depict her mentoring Chibiusa with a blend of playful guidance and unwavering responsibility. Her abilities encompass spacetime manipulation, portal creation, and the forbidden act of stopping time. The Garnet Rod channels teleportation and defensive barriers, while her Eternal form unleashes advanced techniques like the Chronos Typhoon. Her story weaves themes of sacrifice, eternal duty, and the solitude of immortality, framing her as both a guardian of temporal order and a reluctant participant in human bonds.