That time I got reincarnated as a slime Light novel

Satoru Mikami is an ordinary 37-year-old corporate worker living in Tokyo. He is almost content with his monotonous life, despite the fact that he doesn't have a girlfriend. During a casual encounter with his colleague, an assailant pops out of nowhere and stabs him. While succumbing to his injuries, a mysterious voice echoes in his mind and recites a series of commands of which he could not make sense.

After regaining consciousness, Satoru discovers that he has been reincarnated as a Slime in an unfamiliar world. At the same time, he also acquires new-found skills, particularly the ability called "Predator," which allows him to devour anything and mimic its appearance and skills. He stumbles upon Veldora, a powerful 'Storm Dragon', who has been sealed for the last 300 years for reducing a town to ashes. Feeling sorry for him, Satoru befriends the dragon, promising to help him in destroying the seal. They decide to exchange names, Veldora bestows upon him name Rimuru, and receives name Tempest in return. Rimuru then consumes the dragon together with his prison in order to analyze the spell inside itself and eventually free Veldora.

The disappearance of Veldora's aura creates a power vacuum which eventually makes Rimuru the leader of all beings inhabiting the Great Forest of Jura, who accept him as a ruler and together they found the nation of Tempest. With Rimuru's strength, wisdom and idealistic vision the new nation quickly grows in strength and influence. Soon Rimuru and his subjects draw the attention of the nearby foreign powers, from monarchs and legendary heroes to demon lords, some seeking to become their allies, while others intending to take advantage of or destroy them completely.