Satoru Mikami was a typical corporate worker who lived in Tokyo and had never been able to find a girlfriend despite being 37 years old. One day, while walking home from work, he was attacked by an unknown assailant and stabbed. As he lay dying, he heard a strange voice that spoke commands he couldn't understand. When Satoru woke up, he found himself as a slime in an unfamiliar world with new abilities, including the power to consume anything and mimic its appearance and abilities. He met a sealed monster named Storm Dragon Veldora, who had been locked away for 300 years for destroying a town. Rimuru befriended him and promised to help break the seal in exchange for his name and divine protection. Now, with a new goal in mind, Rimuru embarked on a journey to alter his fate by growing accustomed to his slime form and causing ripples throughout the world.