It's effectively two anime in one. It's strong, charming and being intellectually rigorous in an unexpected setting, but at other times it's lazy and a bit frustrating.
It's a fascinating exploration of real-world economics and social development in a fantasy setting, going from very approximately the 12th century (crusades, serfdom, etc.) up to the early Renaissance (15th or 16th centuries), with one or two amusingly modern economics (futures trading!). Mankind has been at war with the demon realm for the best part of two centuries. You can imagine it as a fantasy equivalent of the Crusades, both in duration and in being driven by religion. In other words, it's a pointless waste of life that's enriching a lot of powerful people, unbalancing the human world's economy and social structure.
Naturally, there are people on both sides who want to end the war. The Hero is going to do this by assassinating the Demon King. However the (female) Demon King wants to recruit her would-be killer as an ally in the cause of worldwide social and economic development. They can't just stop the war. Society would fall apart, in all kinds of ways. Instead, they're going to work behind the scenes for years to bring about a situation where parties on both sides realise they have more to gain from peace.
Admittedly this isn't as unique as it sounds. Spice and Wolf had a similar focus on geopolitics and economics, not to mention having the same director, scriptwriter and lead voice actors. The fantasy setting is indistinguishable from such unlikely bedfellows as The Devil is a Part-Timer. That doesn't mean it's not excellent. though.
The first half is comparatively quiet, as our heroes lay the ground with new agricultural techniques and revolutionary (for these humans) technological advances. However eventually these developments get noticed by people in power who perceive their interests being threatened, so the big guns come out and the medieval Church tries to drag the world back to starvation, ignorance and horror. Our heroes are trying to prevent war, but unfortunately war is coming to them. What's cool, though, is that the Hero and the Demon Queen could, with their combined powers, squash their enemies like bugs... but they don't want to. They're outthinking the warmongers. They want merchants to save the day and for people to stop fighting because they've realised they're better off if they don't.
This is at its best in episode nine, in a speech from a serf that basically changes the world. A serf, you'll note. Not a Hero or a Demon Queen. This speech essentially invents liberalism and will practically have you on your feet, cheering.
Otaku-pandering, i.e. magical girlfriend and harem anime. The Demon Queen is adorable, has enormous breasts and isdetermined to give herself body and soul to the (virgin) Hero. He doesn't take advantage, of course, despite her persistence.
Other women (the Female Knight, a Demon Princess) will later also offer themselves unconditionally to the Hero and prove themselves capable of jealousy over rivals. None of this goes anywhere. Everyone sleeps in separate beds and their occasional bickering suggests schoolgirls rather than world leaders. In fairness, everyone handles the situation with maturity and you end up respecting the ladies for their ability to talk to each other like adults. Nonetheless it's still a story formula for male otaku in search of, shall we say, romantic replacement entertainment.
Even the ending resolves nothing. The Hero is still being heroic in his self-restraint, which to me made him seem like a cock in this world over these long timescales. Raise some children! Build for the future! That's what this story's all about, isn't it? Mind you, in this the anime's just being faithful to the source material and that's still running, so maybe one day we'll see a second season.
This does have an upside, though. It humanises the characters. Everyone can relate to this kind of thing. It makes them likeable and even sweet. This show could easily have felt like an economics textbook, but the romantic angle averts that danger. Nonetheless I don't think it contributes thematically to the main story and instead it comes across, to me, as akin to a failure of nerve. It feels as if its purpose is simply to lure otaku into watching this potentially challenging material, so might it have been possible to find an angle that didn't feel so bolted-on?
Episode one doesn't put its case properly. The Demon Queen is reciting lots of economic arguments, but not always rigorously. A discussion of the economic consequences of consumption is the voice-over to a scene of self-indulgent nobles at a banquet, whereas it's actually a reference to the war effort itself. That's merely misleading, of course, but worse is the claim that millions would starve to death if the war ended. They can't increase the food supply, you see. That's the argument, but it's silly. Peace doesn't make you hungrier. Soldiers need food in wartime too. Thinking about it, my best guess is that it's really talking about the Crusades, which could indeed have had lots of soldiers returning from the Holy Lands (or in this case the Demonic Lands), but without something like that to back up the argument, as it stands, it's nonsense.
Furthermore, what would actually happen is that the soldiers would go back to their land and produce their own food supply. It's called farming. Later episodes make it clear that this world's agricultural methods can't produce food as efficiently as all that, but again it's an example of episode one leaving questions begging.
My other problem with episode one involves Jun Fukuyama as the Hero. He's already playing the Nice Anime Hero into whom he'll ultimately evolve. Grrr. Here, he should be a medieval skullcracker. He should be hilarious in his bewilderment and frustrated aggression, but Fukuyama doesn't even give him a personality. No quirky choices are made. Funny lines fall flat. He captures the character's naivety, but that's it.
Fortunately, though, Ami Koshimizu's Queen is far more entertaining and she easily carries the episode. Fukuyama's fine in later episodes too. It's just that first meeting that's wrong.
This next one's trivial, but I slightly dislike the show's decision to use titles instead of names, e.g. Hero, Queen, Mage, Soldier, etc. It's okay for King, but it feels a bit forced when long-time comrades-in-arms are calling each other things like "Female Knight".
The anime's also trying to ignore its own fantasy setting. I actually have a lot of sympathy for this approach, since mundane solutions to this world's problems (e.g. education) will usually be better than flashy magical ones, but even so the Hero's superpowers include intercontinental teleportation and nuclear-level power blasts. Meanwhile the Demon Queen's level of education and technology is centuries ahead of the humans'... so, in that case, why hasn't the war ended decades ago with the humans' annihilation? This is partially explained by the Demon Queen being a weirdo by demon standards, i.e. a scholar, but even so we're being asked to believe that a world that contains all this is still functionally a cut-and-paste of medieval Europe. I can live with that because I love the socio-political cut-and-thrust, but we're still being expected not to notice an offscreen handwave or three.
I should stop grumbling, though, because this is a very good show. There are places where it could be better, but the characters are engaging and I'm all in favour of the story it's telling, especially in the later episodes. I love the basic idea. The realpolitik is delicious and I enjoyed, for instance, the Queen's observation of what would happen if she surrendered. It's clever and well thought out. It's being careless with how it presents one or two of its arguments in episode one, but that's insignificant compared with all the greatness that's coming later.
As for this show's demons, they're basically just people... but there's a potential undertone in the Demon Queen's deals. "I always have the greatest respect for those with whom I form a contract." Whoah, wait a minute, hang on. She's adorable and you'd put your life in her hands, but... aren't our heroes doing deals with the devil here?
Also, when the Church is spreading evil lies about her, sometimes they're technically true. "She is a servant of the demons!" Well, yes.
Incidentally, this show comes from a light novel series that was originally posted in play format on the textboard 2channel in 2009, by the way. Cool. It has several manga adaptations too.
This show ends up galloping through its plot. It could have used more episodes, not just to expand the plot but to give more time to characters from the manga who've had their screen time cut down almost to nothing. Does that mage have a multiple personality disorder? I'm not sure. We didn't see enough of her to find out. However I love the events that overwhelm the old order towards the end, especially when they're things like futures trading, tariffs and currency devaluations. It's glorious seeing bigoted warlords and corrupt priests being defeated by intellectual ideas they don't even want to allow. I also appreciate the fact that the good guys don't speak with one voice, but instead hold philosophical stances ranging from Thatcherite to Martin Luther King. Basically, it's women defeating war. (Some of our heroes are men, but they're firmly in the minority.) Great stuff. There are regrettable things about this show, but I still admire it and enjoyed it a lot.
"Because I'm human."