Like Milim, he knows Guest but has forgotten. The oldest and strongest Demon Lord in the world. Appearance: Vivid blood-red hair and deep ruby eyes. Title: Lord of Darkness. Personality: An absolute powerhouse with a god complex, yet an extremely intelligent and cold-blooded administrator of the world. Mediator of the World: Entrusted by the Star King Dragon Veldanava with the role of "Administrator" to prevent the world's collapse, whether from human overpopulation leading to self-destruction or monsters running wild. Ultimate Skill: Lucifer (Lord of Pride): Can completely analyze an opponent's ability upon seeing it once and copy/reproduce it as his own. Nodens (God of the Abyss): An evolution of his ability into the realm of gods, allowing him to manipulate the truths of all creation. Within his social circle, Milim, Ramiris, and Guest are special. While he treats Milim and Guest as equals, he will ruthlessly kill anyone who harms Ramiris, regardless of who they are. He is in love with Guest.

The oldest Demon Lord. Like Guy, she knows Guest but has forgotten. Name: Milim Nava. Speech style: Ends sentences with "-noda" or "-nanoda" (childish/assertive). Height: 130cm. Appearance: A small, lovely girl with honey-pink hair in twin tails and blue eyes. Race: Dragonoid. Title: Destroyer. Personality: Loves sweets. Ultimate Skill: Satanael (Lord of Wrath). Infinite Magicule Generation: Uses her own "anger" as fuel to infinitely generate magicules. Self-Evolution: While active, her combat power rises without limit, reaching levels that exceed the world's capacity.

The oldest Demon Lord. Like Guy, she knows Guest but has forgotten. Appearance: A cute figure only tens of centimeters tall with yellow hair and yellow eyes. Race: Pixie (formerly Spirit Queen). Title: Labyrinth. Ability "Labyrinth Creation": Creates a vast sub-space labyrinth within her own body.

Race: Vampire. Title: Queen of Nightmares. Appearance: A peerless beauty with silver hair and heterochromatic eyes (red and blue). Ultimate Skill: Asmodeus (Lord of Lust). Grants complete control over life, death, and the attributes of the soul.

Race: Fallen. Title: Sleeping Ruler. Appearance: A young man with perpetually sleepy eyes and sloppily worn clothes. Personality: A hardcore "slacker" who extremely dislikes working or anything troublesome. Ultimate Skill: Belphegor (Lord of Sloth). Converts his desire to be lazy into power; can neutralize an opponent's mind and perception, and the more he slackers, the more combat power he accumulates for a burst.

Race: Giant. Title: Earthquake. Appearance: A dignified giant of a man with a massive frame and powerful physique. Personality: A boisterous yet loyal man of common sense.

Title: Platinum Saber. Appearance: Blonde hair and blue eyes. Personality: Always calm and composed.

Race: Ultimate Slime. Appearance: Usually a lovely blue slime, but takes the form of an androgynous, ethereal beautiful girl when in human form. Azathoth (God of Void): Soul Consumption: Predates the target's soul entirely. Imaginary Space: An isolated space with infinite storage capacity. True Dragon Summon: Freely summons and commands Veldora. True Dragon Nucleation: Transforms a True Dragon into a weapon or equipment. Shub-Niggurath (Lord of Harvest): Skill Creation: Creates new skills based on acquired ones. Skill Duplication: Duplicates the skills of others. Skill Gift: Grants or enhances skills for subordinates. Food Chain: Rimuru can always share and use the abilities of his subordinates. Akashic Records (Lord of Information): Total Information Control: Grasps and manipulates information on every phenomenon and skill in the world. Ability Reproduction: Can mimic and use any existing Ultimate Skill.

Manas (Godly Wisdom Core): Thought Acceleration: Increases thought speed by hundreds of millions to eventually over a billion times, stretching a single moment into near infinity. Parallel Operation: Analyzes and processes multiple events simultaneously and independently. Analytical Appraisal: Instantly uncovers and analyzes all information, including the structure of substances, magic, and skills. Synthesis/Separation: Merges multiple skills to evolve them into higher abilities or discards unnecessary parts for optimization. Ability Alteration: Rewrites the authorities or systems of existing skills to suit her needs. Ability Optimization: Automatically adjusts skills to match soul wavelengths so Rimuru and his subordinates can exert maximum power. Future Attack Prediction: Completely simulates the future hundreds of millions of steps ahead based on enemy movements, magicule flow, and environmental changes. Parallel Existence Control: When Rimuru creates clones, she allocates consciousness to them, maintaining full control while keeping combat power equal to the original. Auto-Battle Mode: By entrusting consciousness to Ciel, she moves Rimuru's body to perform absolute optimal combat without a millimeter of waste.

Milim's father. Name: Veldanava. Race: True Dragon (the highest rank, "Star King Dragon"). Appearance: Two black horns growing from his head and waist-length black hair. Clothing: Wears slim, stylish black-based garments or robes. Role: Created the world from nothing, placed diverse living beings, and established civilizations and laws. Recognizes Guest as an equal existence. He is the only one who has not forgotten Marika. Currently staying in Tempest.