The world is just popping out heroes left and right to deal with the demon lord who is fixing the world's problems.....
The hell kind of dumb ass system is this!?
I saw the other comments, but I thought my two cents would help: I'm taking a perspective from other series, moreso Earthchild, so I think of this world operating on such a system, where it's maintaining homeostasis by having demons cull human populations, and heroes stopping the cull before humsns go extinct, it just got out of hand as society and its drama developed. Dwight (i hope that was his name) and the heroine dying was either a flaw in the system, or the world returning things to zero, leaving everything accounted for, not taking into account the Dorohedoro effect, Dwight returning with knowledge on how to counter the world, effectively becoming an error in its system.