Sidestory of TBGA. (Though you can read it as a standalone story too)
After falling into a coma, Adon, a god from another world, makes the protagonist an offer; Do a job for me, and you'll be able to wake up.
After taking him up on his offer, the protagonist is taken to another world. The only job he is given is to survive.
Although he is reincarnated as the race with the longest lifespan, the dungeons, this brings along many other struggles in his fight to survive and, one day, see his family again.