Professor Souichi Tomoe, a scientist specializing in genetics, engineering, and astrophysics, faced expulsion from the scientific community for unethical experiments involving extreme animal testing and gene manipulation aimed at creating "super life forms." He sold his controversial research to overseas companies, using the profits to buy Tokyo's Sankakusu District and establish Mugen Academy as a front for his ongoing work. His life shattered when a lightning strike caused a laboratory fire, killing his wife Keiko and critically injuring his daughter Hotaru. Desperate, he saved Hotaru by converting her into a cyborg using cybernetic enhancements. Simultaneously, the lightning brought Daimon Eggs linked to the extradimensional entity Pharaoh 90, infecting Tomoe and his assistant. Witnessing his assistant transform into the Daimon-human hybrid Kaolinite, Tomoe willingly offered his soul to Pharaoh 90 and ingested a Daimon Egg, merging with the entity Germatoid to gain the power needed for his daughter's survival and his research ambitions. Leading the Death Busters from Mugen Academy, Tomoe directed efforts to harvest human souls to sustain Pharaoh 90's dying homeworld. His primary objective became creating stable human-Daimon hybrids, termed "Superior Beings" or "Super Beings," through genetic manipulation, cybernetics, and pharmacology. He kidnapped human test subjects, torturing and mutating them into Daimons, using their bodies as vessels for Daimon Eggs. He also created the Witches 5 directly from Daimon Eggs. Tomoe implanted the Daimon Egg of Mistress 9, Pharaoh 90's partner, into Hotaru's body, making her its host. This act further endangered Hotaru's fragile health, demonstrating his psychological and emotional abuse as he prioritized his scientific curiosity and allegiance to Pharaoh 90 over her well-being. His collaboration with the Death Busters aimed to terraform Earth for the Daimons, requiring the extinction of all non-Daimon life. Confronted in his laboratory by Super Sailor Moon and the Outer Guardians after his initial Daimon creations fell, Tomoe transformed into his monstrous Germatoid form. This state granted enhanced strength, durability, energy projection, and regenerative abilities. Sailor Moon ultimately destroyed him using her Rainbow Moon Heart Ache attack. Before his demise, Hotaru acknowledged that the compassionate father she knew had effectively died alongside her mother years earlier. Tomoe's characterization and fate differ across official media. In the manga and *Sailor Moon Crystal*, his descent into villainy stems from ambition and a voluntary embrace of darkness, devoid of redeeming qualities; he perishes following Germatoid's destruction. Conversely, the 1990s anime portrays him as a victim forcibly possessed by Germatoid; he survives the arc, loses his memories, and briefly cares for the reborn Hotaru before her adoption by the Outer Guardians. Musicals introduce further variations, such as his body being possessed by the alchemist Dreadful Berserk in the *Last Dracul* arc, where he creates homunculi like the Death Mannetjes or the Samael Quartet derived from Chibiusa's star seed; these portrayals sometimes retain traces of his concern for Hotaru despite his antagonistic role.