Rimuru Tempest formerly known as Satoru Mikami, is the main protagonist of That Time I Got Reincarnated as a Slime.

Partner and best friend of the True Dragon Veldora Tempest, Rimuru is the founder and King of the Jura Tempest Federation in Jura Forest. He is one of the Demon Lords of the Octagram. He lives in Rimuru City, the Capital city of the Jura Tempest Federation .Rimuru initially appears as a blue-bodied Slime, but upon becoming a Demon Slime, his body turns silver with streaks of gold.

Thirty-seven-year-old Satoru Mikami is a typical corporate worker, who is perfectly content with his monotonous lifestyle in Tokyo, other than failing to nail down a girlfriend even once throughout his life. In the midst of a casual encounter with his colleague, he falls victim to a random assailant on the streets and is stabbed. However, while succumbing to his injuries, a peculiar voice echoes in his mind, and recites a bunch of commands which the dying man cannot make sense of.

When Satoru regains consciousness, he discovers that he has reincarnated as a goop of slime in an unfamiliar realm. In doing so, he acquires newfound skills—notably, the power to devour anything and mimic its appearance and abilities. He then stumbles upon the sealed Catastrophe-level monster "Storm Dragon" Veldora who had been sealed away for the past 300 years for devastating a town to ashes. Sympathetic to his predicament, Satoru befriends him, promising to assist in destroying the seal. In return, Veldora bestows upon him the name Rimuru Tempest to grant him divine protection.