Hotaru Tomoe / Sailor Saturn

Hotaru wears a shoulder-length black bob with a purple sheen at the front and violet eyes to match. Early on she is usually shown in casual clothes or a winter jacket during Mistress 9's control, and like Haruka and Michiru she dons the Mugen Academy winter uniform with blue pantyhose and black flats; out of uniform she favors a black long-sleeved dress.

As Sailor Saturn her costume is a chest-armored white leotard with petal-like shoulder pieces, a dark purple collar, a star-clasped choker, a dark purple skirt over a puffy belt, dark brown bows front and back, laced purple knee boots, and pointed-tipped gloves. A pale heart crystal sits at her chest, a gold tiara holds a white oval gem, and ringed pearl earrings shaped like her planet dangle tiny dagger pendants. Her Super form makes only small changes: a longer back bow, a purple heart on the front, an oval gem in the tiara, standardized glove tips, a striped collar, and a gold star on the choker.

Ostracized by classmates for her strange abilities and sudden mood swings, Hotaru in the Super arc is calm, shy, often gloomy, and warmhearted, while the Saturn side of her is grave and nearly emotionless. Her frailty and the presence of Mistress 9 keep her at a distance from others, and she leads a mostly solitary life until Chibiusa befriends her.

By Sailor Stars her nature is transformed. Reborn and rapidly aged into a young child, she becomes playful and energetic, especially around Haruka, Michiru, and Setsuna, yet turns serious and resolute about her duty. The shift owes much to Saturn's spirit possessing her to restore her memories, and to her awareness that Usagi is in danger and that the Earth nearly perished because of her.

Hotaru is the only child of Professor Souichi Tomoe. A disaster in his genetic lab, caused by the Daimon Germatoid crossing over from the Tau Star System, killed her and injured her father; the entity offered to revive her, then hijacked Tomoe's body while a second being, Mistress 9, took hold of the restored Hotaru. Left frail and prone to mysterious seizures, she can heal small injuries in seconds, while her possessed father founds the Death Busters and arranges Pharaoh 90's arrival without her knowledge.

She meets Chibiusa at a park after chasing a lost hat and the two become best friends. Her fits sometimes let her unconsciously damage Daimons, drawing the outers' attention, and Sailor Pluto reveals she is the reborn Sailor Saturn who could end the world. Once her identity is confirmed, the Death Busters hide her in Mugen Academy, and when Chibiusa is captured, the Messiah of Silence consumes her Pure Heart Crystal and Hotaru's body becomes Mistress 9. Fighting from within, Hotaru finally regains control, destroys Mistress 9, and reawakens as Sailor Saturn, ready to give her life against Pharaoh 90 until Sailor Moon uses her Pure Heart to save her, emerging with an infant Hotaru whom Uranus and Neptune return to her father. In Sailor Stars, Setsuna reclaims baby Hotaru, Saturn's spirit reawakens inside her and ages her rapidly, and she fights as Super Sailor Saturn before being killed with Pluto by Uranus and Neptune, then revived at the end when Serenity cleanses Galaxia. Her power governs death, destruction, silence, and ruin, able to obliterate whole planets, and she can raise force fields strong enough to withstand even Galaxia, wielding Silence Wall and Silence Glaive Surprise with her glaive.