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

Possesses excellent grades but suffers from poor behavior. 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 gave Koro-sensei his name. She has a strong complex about her flat chest. She is a massive fan of sweets.

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

An Archdemon who rules over the demon race... or so he is classified, but his true identity is one of the Primordial Demons, of which only seven exist in the world.

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

The son of the Ogre chieftain whose tribe was 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 princess of the Ogres. 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. She looks like a cool beauty, but her combat prowess is extremely high.

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