But um...there's one problem here. He's not the demon king. He's just a really powerful monster tamer.
It's the title they give to the king of the monsters and from the time he used the job changing book he got the job demon king that had the skill of monster taming.
I was pretty certain that in a couple earlier chapters it was stated that there's an actual demon king. And our MC is not the demon king, from what I remember.
he is the demon king reread it again..
Lol his not smart, i agree even the side characters know of it. The first dumb demon king i read so far. If he won't learn and become more clever he will suffer more along the way, forget creating a nation if yow not smart enough to do it.