That Time I Got Reincarnated as a Slime (Seasons 1–4)

That Time I Got Reincarnated as a Slime (2018) is a fantasy adventure anime you can watch online on iFILM. Satoru Mikami, a lonely 37-year-old office worker, gets fatally stabbed on a city street and wakes up in another world — as a blob of slime.

Reborn under the name Rimuru, he discovers his shapeless body can absorb anything and mimic the powers of whatever it eats, from a dragon's breath to human speech. He frees Veldora, a Storm Dragon sealed in a cave, learns magic fast, and sets out to do something a slime has no business attempting: found a nation where goblins, orcs, humans and beastmen can actually coexist. Every alliance has to be earned, by diplomacy or by force.

Animated by 8bit and based on Fuse's light novels, the series grew across several seasons into one of the defining isekai hits of the decade. What sets it apart is a hero who wins through planning and negotiation as often as raw strength — the nation-building intrigue often beats the fights. Worth a look if generic reincarnation stories have worn thin and you want a world with real worldbuilding. Stream That Time I Got Reincarnated as a Slime (2018) online on iFILM.