Sailor Saturn

Sailor Saturn (セーラーサターン, Sērā Satān) is a fictional supporting character in the Sailor Moon manga, the 1992–1997 anime series created by Naoko Takeuchi and the 2014–2023 reboot that more closely follows the manga. Her spirit resides deep within twelve-year-old Hotaru Tomoe (土萠 ほたる, Tomoe Hotaru), a frail middle schoolgirl who is her lookalike reincarnation, which makes Sailor Saturn her alter ego; entirely apart from how the other nine Sailor Guardians are reborn and their human identities remain separate.

She is the tenth and last of the Sailor Guardians of the long gone Moon Kingdom to be introduced, possessing immensely strong dark powers associated with silence and ruin, nothingness and the void, destruction and death, annihilation and rebirth. Her powers made her a potential threat as she can wipe out a planet, an entire solar system, or reset its evolution. Her deathly powers are necessary for rejuvenation and re-creation to complement Sailor Moon's mighty powers of healing and rejuvenation with powerful moonlight from the Silver Crystal.

Prior to the main events of Sailor Moon, when Hotaru was eight years old, she lived with her parents in Tokyo's Sankakusu District when a freak storm occurred causing a fire that killed her mother Keiko and left her on the verge of death herself. Later admitting that she was meant to die at the time, Hotaru's life was unnaturally prolonged by both the actions of her father Souichi Tomoe turning her into a cyborg and being made a host to the Daimon Mistress 9 whose presence caused Hotaru's body to suffer seizures with only the Tairon Crystal appearing to reduce the pain, only seen in Sailor Moon Crystal's thirteen-episode third season. Wearing clothes to conceal her altered body, unaware of Mistress 9's existence prior, Hotaru was friendless before meeting her best friend, Chibiusa.

By the time she realized Mistress 9's existence, she loses her body to the Daimon as she steals Chibiusa's Silver Crystal to fully regain her strength. Hotaru is also revealed to be the reincarnation of Sailor Saturn who was responsible for destroying the last remnants of the fallen Moon Kingdom Silver Millenium so it can begin anew of Earth. This fact and her power made her feared by the Outer Guardians as they initially intended to kill Hotaru and seal her soul before she could awaken and destroy Earth. But Hotaru, seemingly destroyed when Mistress 9 ripped herself out of the human's body, ended up awakening as Sailor Saturn when Pharaoh 90 appeared and Sailor Moon appeared to have died in a gambit. Though Saturn intended to destroy Earth along with Pharaoh 90, she stops the destruction upon seeing Sailor Moon alive and deemed destroying Earth to make way for the new Silver Millenium not necessary. She then drives Pharaoh 90 to his domain while sacrificing herself to ensure he remains trapped, though Sailor Moon's restoration brings Hotaru back to Earth as an infant. With her father dead, Hotaru becomes the adopted daughter of Haruka Tenoh, Michiru Kaioh and Setsuna Meioh as the four of them reside at an Empire Victorian House.

In the first anime, Hotaru's story is mostly the same except that she was not modified into a cyborg and Mistress 9 had a stronger influence that played a role in her being ostracized by her classmates. Her father also survived the Death Busters' defeat and was allowed to raise her until Setsuna asks for her help in the first part of Sailor Moon Sailor Stars.

Hotaru's age fluctuates during the series; she is first introduced as a twelve-year-old, is reborn as an infant due to Sailor Saturn's spirit forever within her, quickly develops into a young four or five-year-old child around then reaches her proper chronological age after a metaphysical epiphany with Sailor Saturn herself appearing before her to "wake up." When not transformed, her body retains the smaller height of a five-year-old; the exact same height she gained since being reborn.

In the musicals, Professor Souichi Tomoe is only present in a few stages, though Sailor Saturn appears in every musical from the third on. In musicals where Tomoe is absent, Hotaru is presented as being in the care of Haruka and Michiru. During Last Dracul Jokyoku, Hotaru is presented in the care of Professor Tomoe, knowing of the existence of the Sailor Soldiers, yet not awakening as Sailor Saturn until halfway through the musical.

Naoko Takeuchi, the series creator, describes her as delicate, quiet, precocious, and expressionless.