Isekai Kaeri no Ossan wa Shuumatsu Sekai de Musou suru - Vol. 1 Ch. 5

[MangaDex]

 

[Yazas]

new translator ?

 

[Kaarme]

Right, that short flashback did reinforce the assumption that he had no love whatsoever for that other world. I somewhat doubt he betrayed former comrades, it's more probably the world and society merely were such that former friends automatically became enemies, with no particular personal feelings attached. It obviously wasn't a united humanity+other civilised races against the demon king. Human nations, or individual lords, still fought each other as well, so the MC couldn't entirely avoid that situation. Perhaps a particular king sponsored him for a while, sending some experts to help him, but then the MC needed to make progress and leave the country behind. The king wouldn't want the powerhouse to fall into the hands of another nation and those experts suddenly were ordered to kill the MC. That sort of things. For all we know, some lord might have even become a tool for the demon king.

 

[p2x909]

It's like someone had a stroke, and they're relearning how to read.