Manga Forms
土萠 ほたる
A shy, warm-hearted schoolgirl, Tomoe Hotaru was thrown into the middle of circumstances beyond her control, and first appeared in Act 24 (Act 27 in the renewal editions). When she was eight, she was horrifically injured in a fire that killed her mother, Keiko. Her father, Professor Tomoe, rebuilt her maimed body using his resources and technology, making it partially cybernetic. He also made a deal with Master Pharoah 90, implanting one of its eggs in her body, hoping she would become a truly powerful Vessel. Between this and her cybernetic body beginning to give out, Hotaru became very sickly, suffering from frequent seizures and lapses of weakness.
Hotaru first met Chibiusa during a fight with a daimon, and saw her transform into Sailor Chibimoon. The two quickly became close, while the three Outer Senshi became wary of her, and suspected her of being Sailor Saturn. Since the awakening of Saturn meant destruction, they wanted to do anything possible to prevent it from happening, including killing Hotaru, while Chibiusa, Usagi, and the Inner Senshi wanted to protect the innocent girl. It was after learning those intentions of the Outer Senshi that Chibiusa rushed to Hotaru's house. But as fate would have it, Hotaru had suffered a bad seizure, and while under the control of the evil entity within her, ripped the brooch containing Chibiusa's Ginzuishou from her chest, and rendered her near-death.
When she stole and devoured Chibiusa's Ginzuishou, the being within the egg that had been implanted years earlier, Mistress 9, fully awakened, and completely took over Hotaru's body. But remarkably, Hotaru's soul remained. She kept Mistress 9 from escaping her body and letting her power flow freely, and once Mistress 9 swallowed the souls of the four Inner Senshi, retrieved them and Chibiusa's, before escaping to return them to their owners. Once returning Chibiusa's Ginzuishou and reviving her, Hotaru appeared to her for one last time, before fading away.
After Sailor Saturn's awakening and sacrifice, Hotaru was reborn as a baby once Super Sailor Moon, as Neo-Queen Serenity, used the Ginzuishou to resurrect the ruined world. As her father had been killed, Michiru, Haruka, and Setsuna essentially adopted her and swore to raise her.
Around a year later, in Act 39 (Act 44 in the renewal editions), Hotaru had rapidly grown into a toddler. She continued to age quickly, until she finally awakened as Sailor Saturn, giving Uranus, Neptune, and Pluto the crystals that upgraded them into their Super Senshi forms.
セーラーサターン
Just when all seemed lost to Pharoah 90, the three talismans of Uranus, Neptune, and Pluto resonated, and the Senshi feared for her powers of destruction, Sailor Saturn, awakened. However, this awakening ultimately helped save the world, as she first used her Death Reborn Revolution attack to drain power from Pharoah 90, and then bring down her glaive to bring ruin to the world. As Pharoah 90 attempted to escape back to the Tau System to avoid destruction, Saturn followed to lead the way, before commanding Pluto to seal the gateway to the dimension. Along with Pharoah 90, Saturn is sealed away as well. She first appeared in a flashback in Act 30 (Act 33 in the renewal editions).
Her primary role is to wipe out worlds that have run their course, which is the reason for her being feared by the other Senshi initially. However, a part of that duty is clearing the way for rebirth, which can only be brought by the power of the Ginzuishou. She in fact destroyed the remnants of the war-torn Silver Millennium, when she was accidently awakened when the three Outer Senshi gathered because of the destruction. In a twist of fate, the four were all reborn on Earth after those events, when they originally weren't intended to be.
スーパーセーラーサターン
Sailor Saturn's second form, although in the manga it is actually unnamed. (I personally still refer to her as "Super Sailor Saturn" regardless, to avoid confusion.)
This form first appeared in Act 39 (Act 45 in the renewal editions).
(More info coming soon, once I get reacquainted with the manga more.)
「エターナル」セーラーサターン
Sailor Saturn's third form, also unnamed. (I refer to her as "Eternal Sailor Saturn", like a lot of other fans, to avoid confusion, although it is purely a fan term.)
This form first appeared in Act 42 (Act 49 in the renewal editions).
(More info coming soon, once I get reacquainted with the manga more.)
プリンセス・サターン
Sailor Saturn was also the princess of Saturn during the Silver Millennium. Her castle was Titan Castle, which was watched over by Sailor Power Guardian Saturn while she was away.
Princess Saturn appeared in Act 41 (Act 48 in the renewal editions).
ミストレス9
Mistress 9, also known as the "Messiah of Silence", was inside the egg implanted into the critically injured Hotaru. The being was from the Tau Ceti Star System, serving the purpose of opening a gateway for Master Pharoah 90. The source of Hotaru's seizures, she dwelt in the girl, slowly gaining power as the Death Busters strived to awaken her. This awakening finally begun in Act 30 (Act 33 in the renewal editions), when she stole and devoured Chibiusa's Ginzuishou. By Act 31 (Act 34 in the renewal editions), she had fully awakened.
Hotaru's soul, however, remained intact and kept the entity from escaping her body and letting her power flow freely. She also gathered the souls of the four Inner Senshi and Chibiusa as well when Mistress 9 stole and devoured them, before leaving her body. Mistress 9 was now free to leave Hotaru's body, ripping it apart and showing her true form: that of a horrible ghoulish monster.
She then opened the way for Pharoah 90, absorbing all the Senshi's attacks before assimilating with the being. It is then that Sailor Saturn awakens, draining power from the the two entities that were now one, before driving them away by bringing ruin to the world, and then leading the way back to their home galaxy. Sailor Pluto closes the gateway to that dimension, assuring that they could never reach Earth again.
