Do you remember the time when Demons were actually evil? Well, the tags say "Comedy, Romance, Harem". So don't expect anything serious here.
Story: Peaceful demons wants to eat delicious human food, and humans decides to slaughter all demons (using Heroes, obviously) rather than talking and trading with them. This should sound familiar to y'all. If the protagonist is on the Demon's side, then they are usually hated by humans, and the antagonists are religious figures. It's so common and overplayed that I can't even remember a story where humans are good and the demons are bad... Devil is a Part-Timer, Demon King Daimao and MAOYU are a few examples of human religion being the real evil...
My point being, the story itself is lacking from the very first chapter. There is nothing original and no reason for you to read this particular story. Me, I bought the first volume for the "Dirty way" to destroy heroes, I expected something mature, seinen like, should've looked at the tags before buying it.
Characters: The protagonist is maybe, in Japanese standards, evil. He talks about torture and gives a creepy smile, but he is just negotiation using bluffs. Our protagonist is being sold as a "evil anti-hero mastermind", but he's like someone evil from a kids show, not what we adults would call evil. The worst thing he does is giving someone diarrhea... And he is seriously known as the "Demon Lord's evil mastermind". Pokémon has better villains than that.
The Demon Lord is actually almost worth the title he has. But he loves his daughter, and she tells him not to kill humans for some reason. A demon princess doesn't want war, but the human priests do. *sigh* Booooring.
Overall, stories involving Demon needs to be serious for me to enjoy it. This story is far to silly, but at least is pretends to be more serious that it is. Let's give is applauds for pretending. Evil smiles can be hard to do if you're not actually evil.
If you like happy easygoing fantasy stories, you might wanna give this a try. If you don't need Demons to be, well, Demons, then you could find this story good. With a total of 6 volumes, you might have a nice short'n sweet tale right here. Me, I'll stick with the mature demon stories.