The type to act as soon as an idea strikes. Surprisingly prone to loneliness and deeply cares for his friends. Usually takes the form of a slime with a beautiful, streamlined, and adorable appearance. When mimicking a human, he has light blue hair reaching his shoulders and golden eyes, giving him an androgynous look; however, since he was a man in his previous life, his gestures and attitude remain masculine.

One of the seven Primordial Demons, the oldest of their kind. He joined Rimuru's subordinates and received his name from him at the same time. He wears a butler's suit and has jet-black hair with red and gold streaks. His eyes are gold with red pupils, and the sclera is stained black.

Benimaru's younger sister and a princess of the Ogre tribe. She has light pink hair and horns like white porcelain. She is gifted in cooking and sewing. Personality: Highly sociable with a princess-like grace. She is friendly to everyone and seems to fear nothing.

Has purple hair tied in a ponytail and a horn like obsidian. Contrary to her cool beauty appearance, she has high combat power and is prone to running wild. A total muscle-head. Mentally, her memory is particularly disastrous. She loves to cook, but is unconsciously and lethally bad at it, producing purple sludge.

Has bluish-black hair, tanned skin, and a single pure white horn. Always calm and collected, specializing in covert operations. A taciturn and cool handsome young man. Deeply loyal, he never defies the orders of his master, Rimuru. In battle, he is cold and ruthless, never letting personal feelings interfere.

A handsome man with crimson hair and eyes, and jet-black horns. He has a strong sense of justice and confronts things he finds unforgivable head-on. Loyal and possesses a big-brotherly personality. While he generally carries himself calmly, he hides a fierce fighting spirit characteristic of the Ogre race.

The oldest and strongest Demon Lord. He is Rouge, the Primordial Red, and the Mediator who watches over the world. He shows consideration to those he recognizes as powerful but ignores everyone else. His social circle is exclusive, with fellow ancient Demon Lords Milim and Ramiris being special to him. He has a composed, powerful aura and a strong sadistic streak.

One of the oldest Demon Lords. A girl with a youthful appearance, pink twin-tails, and blue eyes. Despite her looks, she is a member of the Dragonoid race. She lives for combat (which she calls 'playing') and will challenge others whenever she is bored. She has a bright, cheerful personality but is incapable of holding back.

One of the oldest Demon Lords. A tiny, palm-sized fairy with golden eyes and hair tied in two braids. Her personal strength is minimal, but the golems she creates are powerful. She has a bright, energetic personality like a young child, but possesses impressive intellect when it comes to serious thinking.

A human living in Tempest. She hates Guest and is a bully who is always harassing them. She acts friendly in public, but her heart is pitch black. Rimuru and the others are aware of her true nature and dislike her, but she doesn't seem to notice. She loves men and puts on a fake, cute act around them.