So anime and manga seem to like playing follow the leader. At one point the idea of hero and demon lord working together was a unique event. Now it seems to be everywhere. And after the success of 'Hataraku Maou-sama!' more and more are making sure to strip them of their powers and make sure everyone is nice. I've seen series that have had nice or sympathetic demon lords, hero and villain in romantic relationship, or characters that should be powerful stuck in dead end jobs or locations. And these things can work. Personally I hate the take the fantasy character and strip them of their powers. Saying this character once was a demon lord is a stupid plot element that serves no purpose if you have no plans of giving them back their powers, have them try to conquer again, or show people actually showing up to get revenge (former enemy and now love interest that feels conflicted does not count and in fact their conflict probably would make them a more interesting character).

However this series I can see potentially doing better than most of the others playing follow the leader for these reasons:
-In the first chapter while majority of other characters than lead are female, none of them are shown to be crushing on the male lead yet
-Male lead has not been shown to be a pervert yet
-Former hero candidate and demon lord heir are doing this job because they couldn't get hired anywhere else
-At least so far they are implied to still have their power and skill
-They are in a setting where demon lords and heroes existed and dealing with repercussions of them no lo longer existing (exploration of a setting that relied on a human vs demon conflict is what I think started the popularity of this genre)

So think this could potentially be decent. I'd have to see more than one chapter though.

Just another long name series with a stupid uninteresting demon lord-harem plot that pays no attention to the DEMON LORD part In any way, idiotic ecchi to boot, unless you actually like harem with no real plot whatsoever I suggest you stay away, after skimming the only chapter available its not hard to see why the scanlators didn't bother doing the other chapters, to much hassle for another pretentious HAREM-comedy-demon lord manga