Tensei Kenja No Isekai Raifu ~Daini No Shokugyo Wo Ete, Sekai Saikyou Ni Narimashita~ (readlitenovel-com)

Sano Yuji, a black company employee, is summoned to another world while finishing his work at home. His profession in the other world, a Monster Tamer, is considered a job that makes it difficult to become an adventurer. However, thanks to some slimes he met, which read several magical books, he gained magical powers…