Luminus Valentin, also known as Luminous Valentine, is a character from That Time I Got Reincarnated as a Slime. She is a female vampire queen, a Demon Lord holding the fifth seat of the Octagram, and the true ruler of the Holy Empire Ruberios. She is one of the oldest Demon Lords and holds dominion over all vampires. Her full title includes God Luminous and Queen of Nightmares. She is a second-generation true Demon Lord, and her origins and how she evolved into a Demon Lord remain largely unknown. She is among the first vampires in existence. In the distant past, she created a city for her vampire kind called Night Rose, but it was destroyed by the dragon Veldora, forcing her to flee. Following this, she used a period of chaos to establish a new religion that recognized her as a goddess, which became the foundation for the Holy Empire Ruberios. She is a high-ranking magical being classified as a High Blood, or True Blood Magic Spirit Princess. Physically, she has a youthful appearance resembling a late-teen or young adult woman, with silver hair tied with a black ribbon, and heterochromatic eyes with a deep crimson right eye and a light sky blue left eye. She has pure white fangs, and often wears black gothic dresses, though she also disguises herself in maid uniforms when she wishes to remain hidden. A cross symbol is imprinted on her chest. Her personality is described as elegant, confident, and authoritative, but she also possesses a playful and mischievous side. She is highly intelligent and strategic, preferring to operate from the shadows rather than seek direct confrontation. She is cautious and distrustful of humans, but adapts her views when presented with strong reasoning, as seen in her interactions with Rimuru Tempest. Her primary motivations include maintaining and expanding her hidden empire, gathering powerful subordinates, and securing the survival of her vampire subjects. She values loyalty and is protective of those who serve her. In the story, Luminus acts as the hidden deity of the Western Holy Church, which worships her as the one true god. The church's doctrine holds that monsters are evil and must be exterminated, a stance that leads to conflict with Rimuru. She allows her subordinate Roy Valentin to act as a stand-in Demon Lord during the Walpurgis council, and her twin vampire servants Louis and Roy Valentin serve as her body doubles and run the empire's public affairs. Her key relationships include the twins Louis and Roy Valentin, whom she fiercely protects, and Hinata Sakaguchi, an otherworlder and leader of the Ten Great Saints, whom she heals and shows great concern for. Her relationship with Rimuru Tempest evolves from wary suspicion to cautious alliance as they find mutual benefit. Among other Demon Lords, she interacts with respect and rivalry, particularly with Milim Nava and Ramiris. She commands a group known as the Clerics of the Seven Luminaries, also called the Seven Celestial Sages, who are powerful heroes blessed with long lives who oversee the training of knights. Her development shows her growing willingness to form alliances and adapt her strategies, particularly regarding her approach to humans and other nations. Her abilities are centered on her Ultimate Skill, Lustful King Asmodeus, which grants her power over life and death. This includes the ability to revive the dead and inflict instant death on opponents, a skill called Death Blessing. She also possesses Re-Birth, which allows her to sense life energy and greatly enhance the regenerative abilities of others, even healing mortal wounds. She can use multiple defensive barriers to block magical attacks, has Magic Sense for perceiving magical energy, and has resistance to time stop, power nullification, and various forms of manipulation. She is also capable of soul manipulation, death manipulation, telepathy, and fate manipulation. Despite her immense power, her reliance on dark magic can leave her vulnerable to light-based or purification attacks. She is an Ultimate Skill user, which grants her immunity to lower-level abilities and makes her power level impossible for weaker beings to appraise. Her combat style combines powerful magic with strategic use of her environment. Over the course of the story, her abilities continue to evolve, showing greater creativity and effectiveness in battle.