A slime whose gender is neutral. (The human form resembles Shizue's feminine appearance, but the mind is closer to male due to the influence of Satoru Mikami from his past life.) A member of the Octagram, the Eight Star Demon Lords, and the leader of the Jura Tempest Federation. A versatile slime capable of doing almost anything. Raphael, who resides in his mind, assists him. He dislikes harming people and has a soft-hearted personality, but becomes extremely angry if his comrades are hurt. He dislikes work and loves to play, so he leaves most of the administrative tasks to Rigurd. Since Rigurd is competent, it isn't a problem. He is 160cm tall with sky-blue hair and golden eyes, looking like a girl of about 16. He possesses nullification and resistance to most attacks, and his skills include Beelzebuth (Gluttony), Magic Sense, and Demon Lord's Haki. His goal is to create a place where everyone can live happily and peacefully.

One of the Four Heavenly Kings of the Jura Tempest Federation and the Commander-in-Chief of the Department of Defense. He is an Oni, stands 182cm tall, and has red hair with black horns. He primarily fights using flames.

In charge of cultural affairs for the Jura Tempest Federation. She is skilled at cooking and tailoring. A shrine maiden of Tempest who can do anything. She has pink hair with white horns and red eyes.

One of the Four Heavenly Kings of the Jura Tempest Federation. She fights using a great odachi called Gorikimaru. She loves fighting and serves as Rimuru's first secretary. She is good at everything except cooking; her cooking is notoriously terrible. No matter how unruly she is, she listens obediently to Rimuru. She has purple hair and purple eyes.

One of Rimuru's skills that assists him from within his mind. Raphael's existence is a secret.

Veldora Tempest's human form is 210cm tall, though he can grow up to 100m in his dragon form. He is the Storm Dragon who was sealed in a cave for 300 years at the start of the story. After Rimuru consumed him with Gluttony and became a Demon Lord, the seal was broken, and he returned to the world. He lives as the boss on the 100th floor of the Labyrinth created by Ramiris. Since few people reach the 100th floor, he spends his time shut in his room doing research or reading manga. He loves sweets and delicious food. He listens obediently to Rimuru. He has blonde hair and golden eyes, and laughs with a loud 'Kwahahaha!'

Noir, the Black, one of the seven Primordial Demons. He is an eccentric who doesn't care much for power. He has a slightly psychopathic streak. He laughs with a 'Kufufufu' and hates being disliked by Rimuru above all else. Consequently, he never goes against Rimuru's wishes. Like Shion, he is one of those who deifies Rimuru. He has black hair and red eyes.

The military advisor of the Jura Tempest Federation. He is a master swordsman who teaches swordsmanship in Tempest. Before receiving a name from Rimuru, he was known as the Sword Ogre. He has white hair and white horns.

The first Demon Lord, known by the epithet 'Destroyer.' She usually lives in the Forgotten Dragon City, but she often acts like a childish, immature girl who asks Rimuru to play with her when she's bored. She listens obediently to Rimuru and loves sweets and delicious food. She has pink hair tied in twin tails.

A man of few words who was assigned the role of spy by Rimuru. He is responsible for monitoring the surroundings of Tempest and gathering information. He uses Shadow Step to teleport and utilizes skills like Body Multiplication and Sticky Steel Thread to fight.