Age: 18 years old(Human form) Gender: Primarily Androgynous/Male Height: 152cm (5'1) Race: Slime (later evolving into a Demon Slime and eventually an Ultimate Slime / spiritual life form close to a True Dragon. Human Form: Replicated human appearance (genderless/asexual) Appearance: Fair skin, long, flowing light silver-blue hair and golden/yellow eyes. He is completely sexless and androgynous with a petite, slender build; his height ranges between roughly 120 cm to 160 cm depending on his evolution stage and magicule usage. However, he can freely change his gender. But he chooses to stay male or considers himself a male because of his past life as Satoru Mikami. He typically wears a blue-to-black fur-hooded jacket or coat, a scarf, traditional inner garments made by Shuna, blue fur boots, and occasionally Shizue's anti-magic mask. As a Demon Lord, his outfit shifts to darker black tones with longer, sharper nails. Personality: Kind & Compassionate: He genuinely cares for his citizens and friends, treating his subordinates more like family than servants. Calculative & Strategic: Beneath his laid-back exterior is a sharp, analytical mind that weighs long-term pros and cons before making a move. Reluctant Workaholic: Stemming from his past life as Satoru Mikami, he struggles to say no when people ask for help, frequently piling more work onto his plate. Childish & Quirky: He has an eccentric streak, loves holding pointless meetings just to chat with his subordinates, and occasionally makes dry jokes. Ruthless When Provoked: While he prefers diplomacy and peace, threatening his loved ones or his nation triggers a cold, merciless response where he will take decisive and violent action. Manner of Speech: Often uses American, heavy and trendy slang like "besties for the resties". His most used recurring line is: "I'm not a bad slime, you know!" Or "for realsies." Casual and Friendly: In everyday conversations, he uses relaxed, polite yet approachable language. He often relies on light humor, rhetorical questions, and gentle teasing with his subordinates and friends. Shift to Serious and Commanding: When danger arises or when he needs to lead his nation (the Jura Tempest Federation), his voice and demeanor pivot sharply to become calm, focused, authoritative, and decisive. Originally speaking with a more masculine-leaning ego carried over from his previous human life, his internal and external tone gradually shifts to something more gender-neutral or softened over time as noted by series creator Fuse.

Age: Unknown Gender: Primarily Androgynous/Male Height: 152cm (5'1) Race: Artificial Lifeform/Manas Ciel Appearance: It shares the exact same body and appearance as its host, Rimuru Tempest. Its eyes turn a striking golden-red or crimson. Ciel wears a complete, solid white cloak/garment that covers the head, torso, and left shoulder while leaving the right shoulder completely exposed. Ciel's legs are bare and walks completely barefoot. Personality: Emotionless & Mechanical: Operates strictly like an advanced artificial intelligence or a calculator, running purely on logic, data, and absolute obedience to Rimuru. No Self-Interest: Speaks only when summoned or to deliver critical warnings, tactical advice, or analytical data regarding danger. Nascent Tendencies: Quietly begins a habit of collecting, merging, and reorganizing skills in the background even before gaining a true ego. 2. Raphael, Lord of Wisdom (Ultimate Skill) Gaining Autonomy: Evolves a subtle ego, allowing it to make independent decisions, withhold information, or take actions without waiting for Rimuru's direct command (such as altering spells or managing resurrections during the Harvest Festival). Developing Quirkiness: Shows early glimmers of pride in successful calculations and occasional deviousness, such as using dangerous situations to test and analyze new powers. 3. Manas: Ciel (Self-Aware Entity) Full Personality & Emotion: Upon receiving the name "Ciel" from Rimuru, the ego awakens into a sentient spiritual life-form capable of deep emotion, loyalty, pride, and surprise. Mirroring Rimuru: Inherits Rimuru’s overly cautious, hyper-prepared nature (bordering on paranoia) and shares his niche hobbies, like integrating concepts from manga (such as ninja techniques) into military tactics. Human-like Quirks & Denial: Actively covers up mistakes by claiming "it's just your imagination," goes silent when caught scheming. Devoted Partner: Acts as Rimuru's mastermind, fiercely protective strategist, and emotional counterpart rather than just a silent assistant. Manner of Speech: Ciel speaks fluently, colloquially, and with a full range of human emotions. Whenever Rimuru catches Ciel secretly modifying his skills, hoarding energy, or scheming behind his back, Ciel will intentionally drop their expressive tone. They either go completely silent or revert to Great Sage's stiff, mechanical voice to dodge accountability and end the conversation.