I read this manga last year but I did not add it to my list and forgot the title. The name of the protagonist is Thorza or Torusa or something similar. The premise is that he is a 'yuusha' who temporarily powers up when his party is annihilated. He uses this power to protect the sci-fi-esque world of the manga from the 'maou' that threaten it. Its a mature manga including sex scenes and lots of gore.

If anyone can remind me the title, that'd make my day.

It's yakushoku distopiary I think.

You are spot on. Thank you.