Excels at information gathering and keeps track of Koro-sensei's weaknesses. He has a quiet and gentle personality. However, he actually possesses a hidden talent for assassination.

Has excellent grades but is a delinquent. He is quick-witted and loves playing pranks. He was the first in the class to successfully deal damage to Koro-sensei.

The person who came up with the name "Koro-sensei." She has a strong complex about her flat chest. She is a huge fan of sweets.

Satoru Mikami, an office worker, was reincarnated as a slime in another world after getting caught up in an incident. His unique skill "Great Sage" evolved into "Raphael, Lord of Wisdom," and he has awakened as a True Demon Lord, serving as the leader of the Jura Tempest Federation and one of the "Octagram."

Classified as an Arch Demon who rules over the demon race... but his true identity is one of the seven Primordial Demons in the world.

One of the Demon Lords of the Fallen race, known by the epithet "The Sleeping Ruler."

The son of the Ogre tribe chief whose people were wiped out by the Orcs. He has crimson hair and eyes with jet-black horns. He has a strong sense of justice and faces unfairness head-on. After receiving the name Benimaru from Rimuru, he evolved into a Kijin and became an ally.

Benimaru's younger sister and a princess of the Ogre tribe. She has light pink hair and horns like white porcelain. Beyond her lovely beauty, she is gifted in cooking and sewing.

A member of the Ogre tribe with purple hair and a horn like obsidian. Though she looks like a cool beauty, her combat prowess is extremely high.

A member of the Ogre tribe. He has bluish-black hair, tanned skin, and a single pure white horn. He is always calm and collected, specializing in covert operations.