Tensei shitara Slime Datta Ken

Lonely thirty-seven-year-old Satoru Mikami is stuck in a dead-end job, unhappy with his mundane life, but after dying at the hands of a robber, he awakens to a fresh start in a fantasy realm...as a slime monster! As he acclimates to his goopy new existence, his exploits with the other monsters set off a chain of events that will change his new world forever!

(Source: Yen Press)