Satan is living in Tokyo and working at McDonald's. (Well, technically it's MgRonald's. This show is full of thinly disguised real franchises.) He led the demonic forces of evil in a bloody war of conquest in the magical land of Ente Isla... and lost. Evil got its arse kicked, although not before lots of death and bloodshed. Satan thus fled through the dimensions to land in our world. His first instinct was to dominate these puny mortals, but unfortunately Japan isn't a magical land and so Satan's powers are effectively one-use. Short of finding a way to replenish his power levels, for day to day purposes he's got to live like a pathetic human.
Hence the part-time job at McDonald's. He's got no money. No, the title doesn't mean that he's only evil from Mondays to Wednesdays.
This show is lots of fun. Simple as that. Sometimes it's very funny, while at other times it turns into an action show as the Devil's enemies track him down and try to turn him into a grease spot. (Hint: not a good idea. When Satan really lets rip, sometimes you can see the impact from space.)
This show has lots of jokes, but they all come from bringing together devils, angels and heroes in a world of working-class poverty and seeing how they evolve. You see, Satan turns out to be quite a nice guy. When he's not sending his infernal armies of hell to murder your father and torch your village, he's a regular guy. His plan for world domination on Earth involves working very, very hard at McDonald's, earning promotion, rising through the ranks, gaining respect and status in human society and eventually earning a position of power that gives him influence across the entire world. This is hilarious because he looks so pathetic as he says it in his McDonald's uniform... until you realise that he could probably do it. He's immortal and pretty good at most things he attempts.
In other words, he's hell-bent on being the best McDonald's employee you've ever seen. Give him a subordinate (the cute and innocent Chiho) and he'd go to war with an archangel to keep her safe. He even becomes public-spirited. This, paradoxically, infuriates the hero Emilia, who's followed him to Earth and knows it's her duty to kill him. This is complicated when the guy's behaving impeccably and you have a strong moral code.
The cast includes:
(a) Satan, usually in the form of an unremarkable young man. (In his demonic form, he's about eight feet tall and horned.) He grows into the show's hero, which should make this the perfect gift for Christian fundamentalists. You'll be cheering him on as he fights God's emissaries, who are capable of telling their minions that their bloodthirsty orders should be followed without question because they're backed up by the moral authority of heaven.
(b) Ashiya, one of Satan's generals. They fled to Earth together and now they're sharing an apartment. Ashiya's more inflexible than Satan and struggles more with the "not being evil" thing, but fortunately he's utterly devoted to his master and obeys all orders without question. If Satan's plan involves working at McDonald's, then Ashiya will assist him in every way he can. Effectively, he becomes Satan's wife. He manages the household budget, looks after the home and protects his master in every way he can. This isn't a sexual relationship, but there's clearly a homosexual reading available. Satan never shows romantic interest in women, even when they're openly in love with him, instead living with another man in a relationship indistinguishable from marriage.
Later a third male shows up, making it a menage-a-trois in the flat. The show has plenty of female characters too, but they're not the ones living together in a flat so cheap that it probably has only one bed. The only heterosexual male is a creepy, villainous archangel who's sometimes played for pathetic laughs but is a potential sex offender.
(c) Emilia, the hero. She's very, very funny, because her reasons for hating Satan are so strong and yet they end up practically a couple because she's so diligent at keeping him under surveillance. Her reactions are priceless when mistaken for his girlfriend. She'd be easily my favourite character in most shows.
(d) Chiho, who's incidentally a favourite of the anime's director. He increased her prominence from the original light novels. Anyway, she's the only regular who's all-human. She has no superpowers and as far as she's concerned, Satan is just her co-worker at McDonald's. You might thus expect her to be nothing but plot wallpaper, but in fact she's adorable and a key element in humanising our anti-hero. For starters, she's in love with him. On eventually learning about his demonic identity, she's more worried about him returning to his realm than about the fact that HER CRUSH IS SATAN. I also like her reaction to the threat of having her memory erased.
This isn't at all a fanservice show, by the way, but Tomoko saw a bit of male gaze in there. The closing credits in the early episodes are easily the worst for that, being a slow pan up an exploitative picture of Chiho, drawn by the director. (The studio didn't get either the opening or closing credits done in time, so it's episode six before we have completed versions of both.)
The show goes up and down a little. Episode one doesn't find the laughs, because it's mostly set-up and because Emilia hasn't shown up yet. There's nothing wrong with that, though, since personally I'd call this a light-hearted drama rather than an out-and-out comedy. The show's second half also feels more relaxed than the first half, because the characters have settled into a status quo and our demonic heroes seem to have given up on evil. The early episodes had more bite. Oh, and I didn't quite buy Satan being lent out to that other branch as a star employee in episode ten, because he appeared to be being used as just another anonymous spod manning the tills. (The crocodiles were extra-curricular.) That said, though, I'm a fan of the whole show and I'm hoping for a second season. It only came out last year and there's still plenty of un-adapted source material, so anything's possible.
This is a lovely show. Sometimes it's hilarious, sometimes it's charming and sometimes it's just plain cool. It's awesome to see Satan showing up to protect his friends, especially given that his enemies aren't far off his power level. I also like the subversive theology, in which Heaven vs. Hell is clearly the good guys vs. the bad guys... for about five minutes, until things get darker and a lot more complicated. Demons/villains in this show are male, while angels/humans are female, although I'm glossing over a lot of complications and Venn diagram overlaps there. It's a fairly light show and its purpose is entertainment, but there's nothing wrong with that. It's quite intelligent. It's got an unusually powerful reason for its funny character conflict. I bought it hoping that it would be good enough to give as a Christmas present and it's lived up to expectations. Recommended.