Satoru Mikami (「三上悟 Mikami Satoru) is the main protagonist of Tensei Shitara Slime Datta Ken. After death, he reincarnated as a Slime in a different world who was later named Rimuru by "Storm Dragon" Veldora.
He has black hair and genuine eyesight that only people with a kind personality has.
His jokes lacked both delicacy or tact, and he was often told to keep his mouth shut.
After leaving college, he joined a major general contractor firm and lived alone till the age of 37, never having a girlfriend. Filial duty was left to his older brother, his life was essentially that of an independent, single noble. Neither short of height, or wanting of a good face; yet unpopular. He tried exerting effort into finding a girlfriend after confessing thrice. But after being dumped, his heart was left shattered.
He was stabbed protecting Tamura from a thief. Satoru's soul linked with a spawned monster in another world. Into a dimensional crack so small that no eye could see. His soul linked with a mass of demonic energy. This mass was the origin of demons, and to Satoru who had linked to it, his thoughts as a base, the mass constructed a body. What is normal is essentially an impossibility with an astronomically small chance of occurrence, Satoru was reborn as a monster in another world. And that monster, the Slime, became Rimuru Tempest.
After the Tenma Great War had subsided and things became orderly and peaceful, Rimuru could finally relax. However, he had one final lingering regret. Using Teleportation and Time Warp of his Void God Azathoth, he was able to leap across dimensions and return to his former world, right before the time he was stabbed as Satoru.
As the stabbed Satoru lay in front of Tamura, taking his final breath, Rimuru showed up and moved Tamura aside to heal him. Using his body as a visual shield, Rimuru was able to hide his healing method and also the act of him placing a jewel, the Soul Core, inside Satoru's body. After healing, Rimuru told Tamura that he didn't need to clear his browser history nor hard drives and that Satoru will explain the rest after he wakes up; leaving quietly out of the scene.
Satoru then woke up in a hospital, confused as to all the new memories he has was a mere dream or not. Moments later, Tamura entered his room and explains that a beautiful woman, one who could beat any kind of model even, came and revived him back to life after being stabbed. That was when he realized that none of it was a dream. he realized that what had happened was a kind of prank by him, Rimuru. That Soul Core was Rimuru's means of Parallel Existence, meaning him right now was both Rimuru and yet not Rimuru.
He relaxed and asked Tamura if he would believe him if he said that he died and got reincarnated into a different world or not, to which Tamura agreed to, saying that, the woman oddly had an atmosphere similar to him. And that was when he told him the elaborate story of 'That Time He Got Reincarnated as a Slime'.
- In Episode 6 "Shizu" it reveals that Satoru Mikami sometimes goes on the internet to look at pictures of female "Elves."
- In the Epilogue, it is revealed that Diablo accompanied Rimuru to his original world. While Rimuru was willing to forgive the man who stabbed him, Diablo wasn't. He exposed the killer to a technique called Eternal Pain and etched torment on his soul to cause 1,000,000 times the pain that he causes others.