I'm looking for a manga about this guy getting isekai'd into a jungle world. He lives there for a couple hundred years and then he goes back, and when he tells people, they don't believe him because there was no such thing as a jungle world; there are four isekai worlds, but only three of them are known.
He then basically takes the dungeons in the real world by force with his overwhelming skills that he learned over a couple hundred years surviving in the jungle.
It's called The Druid of Seoul Station:
What started out as an ordinary day turned upside down when an unknown catastrophe struck Earth, transporting Suho Park to a different planet. He eventually learns how to adapt and fight for his survival in this foreign world, but one day, just as suddenly as he was sucked into this new planet, Suho is pulled back to Earth. He quickly learns that return to life as he remembers it is no longer possible, as Earth is in constant battle with monsters who’ve managed to infiltrate the planet. How will Suho fight against the monsters attacking Earth, and will he be able to survive this time with his current skills?
It can be read for free on WEBTOON.
