Hotaru Tomoe serves as the civilian identity and modern incarnation of Sailor Saturn, Guardian of Silence and Destruction. Daughter of Professor Souichi Tomoe and Keiko Tomoe, she witnessed her mother die in a laboratory accident during her childhood. This event left Hotaru severely injured, compelling her father to perform experimental cybernetic modifications to save her life, transforming her into a cyborg. A Daimon egg linked to Pharaoh 90 was implanted during this process, resulting in possession by the alien parasite Mistress 9. This caused chronic illness, seizures, and profound social isolation. Attending Mugen Academy, Hotaru faced ostracization due to her health and unexplained abilities. Her life shifted upon befriending Chibiusa, who displayed no fear of her powers. Hotaru demonstrated the ability to heal Chibiusa's minor injuries during an early encounter, though the effort further weakened her under Mistress 9's influence. As the entity's control intensified, it distorted Hotaru's body into an adult-like form and stole Chibiusa's Silver Crystal to fully awaken Pharaoh 90. Despite the possession, Hotaru's spirit resisted internally, protecting Chibiusa's soul and the Silver Crystal while communicating with her friend to encourage defiance. Sailor Saturn awakened during the climax against Pharaoh 90. As the emissary of destruction and rebirth, she wielded the Silence Glaive, a weapon capable of annihilating planets or star systems to enable renewal. Her initial uniform featured petal-like shoulder pads, a maroon chest bow with a crystalline brooch, and a choker with a star pendant. Upon awakening, she prepared to destroy Earth alongside Pharaoh 90 but halted upon seeing Sailor Moon alive, deeming planetary rebirth unnecessary. She then forced Pharaoh 90 back to his dimension and sealed the gateway, sacrificing herself. Following this sacrifice, Hotaru was reborn as an infant, free of cybernetics and Mistress 9. Adopted by Haruka Tenoh, Michiru Kaioh, and Setsuna Meioh, she was raised in an Empire Victorian House. Hotaru aged rapidly from infancy to adolescence within weeks, regaining her memories after a metaphysical encounter with Sailor Saturn's spirit. This reunion fully integrated her civilian and Sailor Guardian identities, enabling her to reawaken as Sailor Saturn in later conflicts. Her powers evolved: Super Sailor Saturn (accessed via the Saturn Crystal) featured an upgraded uniform with a translucent wing-like shoulder pad and a heart-shaped brooch, while Eternal Sailor Saturn adopted a streamlined design with a two-layered skirt, star-shaped tiara gem, and elongated gloves. In later story arcs, Hotaru displayed advanced cognitive abilities like memorizing entire books, though she lacked practical street smarts. Her bond with Chibiusa remained central, and she exhibited protective instincts, notably safeguarding the corrupted Sailor Quartet during Queen Nehelenia's threat. Confronting Sailor Galaxia, she attempted to defend Sailor Pluto but was killed alongside her; both were later resurrected through Sailor Moon's intervention. As Princess Saturn during the Silver Millennium, she resided in Titan Castle on Saturn's moon Titan, remaining dormant until the kingdom's fall. Her name carries symbolic weight: "Hotaru" (firefly) references Japanese mythology linking fireflies to spirits of the dead, while "Tomoe" (earth/sprouting) incorporates the first kanji of Saturn's Japanese name, "Dosei." Together, her name translates to "firefly sprouting from Earth," reflecting her duality as a herald of ruin and renewal.