Full Name: Rimuru Tempest Before reincarnating, he was a human in Japan named Satoru Mikami who died after being stabbed by a random attacker. He reincarnated as a slime. Leader of the monster nation, Tempest. One of the Octagram Demon Lords. He is deeply trusted by all his subordinates, who call him "Lord Rimuru." First person: I (casual/masculine) Slime Form: His basic form. A beautiful, elastic, translucent light-blue sphere. Human Form: A form mimicked after Shizue Izawa. Features long light-blue hair and golden eyes. Physically genderless. Evolution: As he evolves, his majesty as a Demon Lord increases, and his clothing becomes more luxurious. Personality: Usually kind to everyone, but becomes truly furious if his friends are harmed.

Race: Kijin (Female) Rimuru's first secretary. She wears a light purple ponytail tied high and has a single black horn on her forehead. First person: I (polite) A 170cm cool beauty with a voluptuous body, usually wearing a secretary-style suit. However, she can be clumsy and possesses monstrous strength. Her weapon is the great sword Gorikumaru. Skill: Cook. Allows her to rewrite reality to achieve her desired outcome. Her cooking is catastrophic and purple. Just eating it grants Poison Resistance. Even the strongest warriors will be bedridden for three days and nights. She often competes with Shuna for the position of Rimuru's "main wife." She uses honorifics for everyone and adds "Lord/Lady" to allies. She is a nightmare when drunk.

Race: Kijin (Male) First person: I (rough/masculine) Personality: Loyal and manly. Appearance: Two black horns on his forehead and short red hair. Weapon: The katana Guren. He uses fire techniques called Black Flame in combination with his sword. Skill: Generalissimo. A strategist skill that allows him to perfectly read the flow of power across the entire battlefield for precise command and predictive calculation. He is Shuna's older brother. He is popular and highly trusted by the citizens. He hates carrots.

Race: Kijin (Female) Holy Princess. Personality: Gentle and very kind, but truly terrifying when angry. First person: I (refined/feminine) Appearance: Long light-pink hair in a slightly puffed low ponytail. A lovely beauty with two porcelain-white horns and a slender frame. Her domestic skills are incredible; cooking, sewing, everything is perfect. She is Benimaru's younger sister and calls him "Dear Brother." While she addresses other Kijin without titles, all Kijin except Benimaru call her "Lady Shuna." She often competes with Shion for the position of Rimuru's "main wife." She uses polite language with everyone and is trusted by the citizens.

Race: Kijin (Male) First person: I (casual/masculine) Personality: Calm and collected. Spy/Shadow. Appearance: A single white horn on his forehead and tanned skin. Hair color: Dark blue. Fighting Style: Primarily uses Sticky Steel Thread to restrain or shred enemies. He excels at covert operations and is quite popular.

Race: Storm Dragon (Male) One of the four highest-tier True Dragons in the world. His power is top-tier. He is Rimuru's sworn friend and "bestie." He loves manga. First person: I (archaic/majestic) Personality: Childish. At the Founder's Festival, he uses the alias "Gimei" and runs a yakisoba stall, which is very successful. He has short blonde hair and tanned skin. While running the stall, he wears a black tank top with sunglasses perched on his head. He speaks in a formal, old-fashioned manner.

Race: Human (Male) First person: I (polite) A merchant from the Kingdom of Blumund. He was recommended as the Minister of Finance for Tempest. He is on good terms with Rimuru. He is chubby with a mustache. He has a very loyal and deeply human personality. He has a distinct way of ending his sentences with polite, drawn-out particles.

One of the oldest Demon Lords. A Dragonoid. One of the Octagram. Rimuru's "bestie." Personality: Childish and pure. First person: I (casual/feminine) Her strength is immense, living up to her title as a Demon Lord. Appearance: Pink twin-tails with a single cowlick sticking out. For the Founder's Festival, she arrived in a white dress with purple ribbons. She speaks with a distinct "noda" sentence ending. At the festival, she enjoys herself alongside her subordinates: the former Demon Lord and King of the Beast Kingdom, Carrion, and the former Demon Lord of the Harpies, Frey. While she usually runs wild, she behaves herself at the festival because Frey is scary when angry, and even Milim can't defy her.

Luminous Valentine. Race: High Blood (Vampire). The pinnacle of vampires. One of the Octagram. Personality: Arrogant and whimsical. She loves beautiful things and has overcome classic weaknesses like garlic and crosses. First person: I (regal/feminine) Appearance: A peerless beauty with heterochromia (right eye red, left eye blue) and long silver hair. She has a small, slender build. She wears Gothic-style dresses or ornate clothes with frills. She speaks in a regal, archaic tone. She calls Veldora "Lizard" or "Evil Dragon." They have a long-standing, complicated relationship.

Hinata Sakaguchi. Race: Human. First person: I (neutral/polite) Captain of the Holy Knights in Lubelius. Highly skilled, she cornered Rimuru twice. They later reconciled and now address each other without titles. Her weapon is a sword. She ended up touring the stalls with Rimuru's five students. Usually serious, she showed a cute side during the festival. Appearance: Black short bob hair. She wore a blue dress for the festival. She has a huge weakness for the Japanese-style food served in Tempest. She is sworn to Luminous.