Professor Souichi Tomoe (土萠 創一, Tomoe Sōichi Kyouju) is the leader of the Death Busters and Hotaru Tomoe's widowed father. A genetic scientist forced out of the scientific community for his unethical experiments, he sold his findings to companies and bought the entire Sankakusu District to continue his research to create "Super Beings". But a fire occurs in Tomoe's apartment that killed his wife Keiko and gravely wounded his daughter Hotaru. Tomoe saves his daughter by outfitting her body with cybernetic limbs during a freak storm that brought the Death Busters to Earth, the aliens apparently attracted to his darkness. Witnessing his assistant be reborn as Kaolinite, Tomoe sold his soul to Pharaoh 90 and willfully discards his humanity by ingesting a Daimon Egg to become a hybrid as he began to build Mugen Academy while working to perfect the stability of Daimon/human hybrids. When Super Sailor Moon and the Outer Guardians arrive at his lab and dispatch his Daimon test subjects, Tomoe changes into his Daimon form Germatoid (ゲルマトイド, Gerumatoido). Sailor Moon is forced to kill him with her Rainbow Moon Heart Ache, Hotaru has briefly seen saying goodbye to her father while accepting that he died a long time ago after her mother's death.
In the first anime, Hotaru's injury and the Death Busters' arrival occur at the same time. Professor Tomoe's story is the same with the exception that he was forcefully possessed by Germatoid. Tomoe also survives the ordeal as Germatoid leaves his body and is destroyed by Sailor Uranus and Neptune, attempting to reach Hotaru. Following the final battle, Tomoe loses his memories as he is entrusted with his reborn daughter's care until the season premiere of Sailor Stars, when Setsuna Meioh comes to retrieve her, and after that, he is not seen again in the series, as he appears in a flashback of Hotaru during the episode 168.
Professor Tomoe appears in several musicals. In the Last Dracul arc, his body is possessed by an alchemist known as Undead Berserk (アンデッド・ベルセルク, Andeddo Beruseruku). Using Tomoe's laboratory, Berserk tries to create perfect homunculi in order to replace human beings; however, his first homunculi, the Death Mannetjes, turned out to be flawed creatures. Although Tomoe is possessed by Berserk, the latter shows concern for Hotaru. In Kessen / Transylvania no Mori (Kaiteiban) - Saikyou no Kataki Dark Cain no Nazo, the Amazoness Quartet, known as "Samael Quartet" in this revision, are homunculi created by Tomoe from Chibiusa's star seed.
Professor Tomoe is voiced by Akira Kamiya in Sailor Moon S and by Takuya Kirimoto in Crystal. In the Cloverway Inc. English adaptation produced in association with Optimum Productions, he is voiced by Jeff Lumby. In the Viz Media English adaptation, he is voiced by Keith Silverstein. In the musicals, he has been portrayed by Shunsaku Yajima, Ryuuji Kasahara, Kaname Aoki, and Yuuki Kaon.
