True Identity: Formerly human (a 37-year-old male, single office worker). Race: Slime (later evolves into "Slime Lord," "Ultimate Slime," etc.). Personality: Basically good-natured and a pacifist. Values his comrades and strives for nation-building. Main Abilities: Predator: A powerful skill that allows him to take opponents into his body and make their abilities and knowledge his own. Great Sage: A convenient skill that investigates and explains various things in his mind; later evolves into "Wisdom King Raphael." Mimicry: Can freely change into the form of humans he has met or back into a slime.

Name: Milim Nava. Title: Destroyer. Race: Dragonoid. Personality: Innocent and often childlike, but extremely terrifying when angered. Loves sweets. Strength: One of the few "True Demon Lords" in the world, boasting an overwhelming amount of Magicules. Skill: Possesses "Dragon Eye," which allows her to see through an opponent's abilities and strength. Relationship with Rimuru: Was bribed (appeased) with honey and formed a bond as Rimuru's "Bestie." Since then, she has been a good supporter and ally to Rimuru.

Real Name: Shizue Izawa. Alias: Conqueror of Flames. Features: Summoned to another world from wartime Japan (Tokyo). Harsh Past: Experienced the Great Air Raid of Tokyo as a child and was summoned to the other world by Demon Lord Leon Cromwell. At that time, the high-ranking spirit Ifrit was forcibly possessed into her body. Adventurer Era: Feared for many years as the Conqueror of Flames while serving the people, she later guided the Hero Masayuki and Hinata Sakaguchi. Deviant: A unique power Shizue created to prevent Ifrit from running wild. It can "Integrate" different things or "Separate" properties. Flame Giant (Ifrit Possession): Houses the high-ranking spirit Ifrit within her body, possessing combat power to manipulate high-temperature flames and fireballs. Her physical abilities and resistances are also very high due to Ifrit's power. Spirit Magic / Fire Magic: Attack magic that releases flames at will. Spatial / Daily Magic: Spatial storage and daily life magic like Clean Wash. Swordsmanship: Possesses high sword skills as an Otherworlder, fighting with sharp strikes imbued with Magicules.

Name: Diablo (formerly Noir, Primordial Black). Race: Demon, Demon Peer. Characteristics and Charm: Loyalty to Rimuru: Calls Rimuru "My Lord" and holds absolute loyalty and deep adoration. Overwhelming Combat Power: Possesses vast experience as a Primordial Demon and extraordinary magic and combat strength. Butler-like Demeanor: Usually speaks politely, but is ruthless and cold toward enemies.

Race: True Dragon (Storm Dragon). Title: Storm Dragon, Catastrophe-class. Story Characteristics: Sealing and Release: Was sealed in a cave for 300 years after a battle with the Hero (Chronoa), but was "Predated" by Rimuru, analyzed in his stomach, and later resurrected. Incarnation (Human Form): Obtained a body using Rimuru's clone as a medium, allowing him to take a blond human form. Personality: While he looks like a majestic dragon, inside he loves manga and rumors, and has a cheerful, slightly mischievous personality. He is connected to Rimuru via a Soul Corridor and shares a strong bond of trust. Overwhelming Magicules: Boasts one of the highest Existence Values (amount of Magicules) in the world. Ultimate Skill: Possesses "Storm King Veldora," which governs the power of storms, granting immense authority over tempests and probability manipulation.

Race: Ogre ⇒ Kijin ⇒ Fair Oni. Family: Benimaru (Older Brother). Characteristics and Abilities: High Production and Internal Affairs Skills: A genius at cooking, sewing, and weaving. Contributes greatly to the development of Tempest's food, clothing, and shelter. Talent for Magic and Analysis: Possesses excellent magical sense, analytical ability, powerful barrier techniques, and high intelligence to perceive the nuances of holy and demonic forces. Appearance and Personality: Has a gentle and lovely appearance, but can emit terrifying pressure while smiling when angered. Unique Skill "Analyst": The ability to thoroughly analyze target magic or phenomena. Based on the results, she can perform "Law Manipulation" to disrupt the structure of an enemy's magic or cause it to go out of control.

True Identity: Former Captain of the Lizardman Guard. During her brother Gabil's rebellion and imprisonment, she escaped the village to seek help from Rimuru. Naming: Received the name "Soka" from the protagonist Rimuru Tempest. Evolution: Through the naming, she evolved from a Lizardman into a humanoid "Dragonewt." Combat Style: Specializes in combat combining stealth skills like "Shadow Motion" taught by Souei with the flight and mobility unique to Dragonewts. Strength: Through Souei's rigorous training and the Harvest Festival gifts from Rimuru's awakening, she has grown to a level of combat power comparable to high-ranking Majin or Demon Lord executives. Dragon Warrior Transformation: The ability to transform into a combat-specialized form. Stealth / Ninjutsu: High scouting, assassination, and stealth skills honed under Souei.

Race: Vampire (Progenitor). Title: Demon Lord. Personality: Haughty and whimsical, loves beautiful things. On the other hand, she is particular about food and music (especially sacred music). Identity and Disguise: At the Walpurgis Council, she initially attended disguised as a "Maid" attendant, setting up her body double Roy Valentine as the Demon Lord. Abilities and Strength: Ultimate Skill: "Lustful King Asmodeus." Authority: Governs life and death, allowing her to manipulate the life force of living beings at will.