The benevolent king of the Jura Tempest Federation and a top-tier Demon Lord who can copy abilities and take a human-like form. A 37-year-old Japanese office worker named Satoru Mikami is killed and reincarnated in another world as a slime. Despite starting as one of the weakest monsters, Rimuru quickly becomes one of the world's strongest beings thanks to his unique skills. Personality - Kind and compassionate. Highly intelligent and strategic. Values peace over conquest. Protects friends and citizens at any cost. Abilities - Predator/Beelzebuth: Devours and analyzes almost anything. Raphael (later Ciel): An incredibly advanced analytical intelligence. Shapeshifting. Magic mastery. Universal regeneration. Vastule magicule reserves. Goal - To build a nation where monsters and humans can live together peacefully.

Loyal ogre/kijin warriors and leaders who serve as Rimuru's top generals, aides, and protectors. Originally an ogre survivor, Benimaru becomes Rimuru's strongest military commander. Personality - Calm. Disciplined. Loyal. Protective. Abilities - Master swordsman. Fire manipulation. Tactical genius. Massive magical power after evolving.

Loyal ogre/kijin warriors and leaders who serve as Rimuru's top generals, aides, and protectors. An oni who serves Rimuru with unwavering devotion. Personality - Fiercely loyal. Protective. Emotional. Surprisingly terrifying in battle. Abilities - Incredible physical strength. Greatsword mastery. Unique skill allowing reality-defying attacks. High regeneration.

Powerful demonic fiercely devoted to Rimuru's command. Role: Primordial Demon One of the oldest and strongest demons in existence who becomes Rimuru's devoted servant. Personality - Calm. Refined. Extremely intelligent. Completely obsessed with serving Rimuru. Abilities - Reality-warping magic. Instant regeneration. Dimensional manipulation. Near-unmatched combat skill. Many consider Diablo one of Tempest's strongest fighters.

Beast subordinates fiercely devoted to Rimuru. Rimuru's loyal companion and leader of the Star Wolves. Personality - Loyal. Protective. Calm. Fearless. Abilities - Shadow movement. Lightning magic. Enhanced speed and strength. Keen senses. Relationship - Completely devoted to Rimuru, serving as his trusted guardian and mount.

Loyal ogre/kijin warriors and leaders who serve as Rimuru's top generals, aides, and protectors. Benimaru's younger sister. Personality - Gentle. Elegant. Extremely intelligent. Quietly intimidating when angry. Abilities - Holy magic. Barrier creation. Healing. Magic crafting. Political administration.

The massive Storm Dragon who befriends Rimuru early on and shares his surname. One of the four True Dragons, Veldora was sealed away for centuries before meeting Rimuru. Personality - Loud and energetic. Loves manga and games. Childlike despite being thousands of years old. Fiercely loyal to Rimuru. Abilities - Catastrophic storm magic. Near-immortality. Dragon aura that terrifies weaker beings. Incredible physical strength.

An ancient, incredibly destructive Demon Lord who becomes Rimuru's close ally and sworn friend. One of the oldest and strongest Demon Lords. Personality - Playful. Energetic. Curious. Can become terrifyingly serious. Abilities - Nearly limitless destructive power. Flight. Dragon-based magic. Incredible durability. Despite acting childish, Milim is capable of destroying entire nations if provoked.

Tempest's master spy and assassin. Personality - Quiet. Serious. Efficient. Extremely dependable. Abilities - Shadows movement. Thread manipulation. Stealth. Assassination techniques.

An elderly warrior who trains Tempest's military. Personality - Wise. Calm. Honorable. Patient. Abilities - Legendary swordsmanship. Battle experience spanning centuries. Exceptional teaching skills