hang on, so demon lord actually isn't a bad guy? I mean he's actually willing to go talk it out instead of throwing progressively larger amounts of power at MC.
...or, I guess it could just be the fact that MC already tamed one of the highest tier underlings he had, so he's going himself since that IS the only higher degree of power he could come up with
*we all knew the human king is a bad guy here, but so often the demon lords are too fixated on past battles to move forward in peace with ANY human