--- The technical aspects
Landscapes and buildings in this anime are generic, they’re the kind of stuff you can find in any garbage isekai or crypto-isekai. Though they don’t look ugly, they aren’t that well drawn, except maybe in the first episode. The character designs are… very meh. Some are decent, like Shera and Rem, as they fulfill their purpose of being cute, but most of them (Celestine, Emile, Galford and others) are extremely lazy. Take the protagonist Diablo for example: he has the generic video game demon character design, meaning he’s just a normal human with small horns on his head (in his case, they are fake) and some weird tattoo on his face, much like the demons in Tensei Shitara Slime Datta Ken and the demon lord in Hataraku Maou-sama! At least he look somewhat like a demon lord, contrary to some series where the “demon lord” is just a regular-looking human with overpowered abilities. There’s also the usual bullshit where males of the evil race are monsters and the females are human females but they have horns and pointy ears – they wouldn’t be fuckable if they were monsters, huh? As usual, magic in this anime is mostly just cheap and ugly magic circles. The animation is okay most of the time, though there are some moments with very little actual animation, and there can be inconsistencies in the characters’ faces.
Sound-wise, the background music isn’t good, sometimes even bad. Same for the generic opening. I’d say that the voice-acting is mostly good, except from Shera’s irritating voice.
--- It’s an ecchi
So our protagonist is summoned into his favorite game Cross Reverie (light novel writers stop using random foreign words challenge) by a cat-girl and an elf, who both cast an enslavement spell on him to make him their summon, but the spell is reflected by one of Diablo’s skills, and the two girls are turned into his slaves. You can see where this is going. This anime is a ecchi of the harem type, with the usual stuff like the protagonist sharing a bed with his two slaves, ear nibbling, boob fondling, skimpy clothing for almost all female characters (Rem, Shera, the guild master, the slave trader, Edelgard, Klem), jokes about boobs’ size, suspicious camera angles, and bath scenes with the girls groping each other.
Is the ecchi well done? Since it is very predictable and makes the female characters uninteresting, ecchi is always bad. But in this anime, the ecchi elements are surprisingly decent, at least for the first half of the series. After that it gets more and more stupid, as the series attempts to justify the ecchi elements with the plot: touching the girls’ breasts replenishes magic, staring at Shera’s boobs allows Diablo to makes potions, and to resurrect the demon lord Krebskulm who is kept inside Rem, Diablo has to finger her – yeah!
--- There are rare moments where the comedy is decent
… with Emile Bichelberger’s appearances, for example, but only in the few early episodes, as the series gets more serious after that – serious meaning cheesy and boring stuff about friendship and the like. One thing that is quite funny to see in the few early episodes is that, being a socially awkward incel, the protagonist has to role-play his demon lord character to be able to talk to people.
--- Sadly, this gets repetitive quickly
Not only this, but as the series progresses, Diablo speaks less and less like a demon lord, and more and more like your average otaku protagonist, saying sappy lines about friendship, making your own choices and so on. In short, Diablo is as much of a demon lord as Maou Sadao in Hataraku Maou-sama!, meaning he’s not a demon lord at all. In the entire series there is not a single time where he acts like an actual demon lord, except maybe from one particular moment in ep.4. Most of the time he helps people, saves his friends, fights bad guys, is idealist, and spares his enemies – even if they tried to rape and kill his friends!
--- The protagonist’s actions are incoherent
In ep.4 Diablo fights a Fallen (the Fallen being the bad guys of the series) who tried to kill Rem, since he is overpowered he has no trouble defeating him, and then he kills him in a really painful manner to punish him for harming his friend. But later in the series, when he defeats the Elven king who tried to rape Shera, Shera makes Diablo spare him because “he’s family”… Seriously? Same thing for Galford who attempted a goddamn genocide. Same thing for Edelgard and Alicia who tried to bring back Krebskulm, the true demon lord of Cross Reverie. Same thing for the demon lord Krebskulm, who is forgiven for her past crimes since she is actually just a normal loli. Yeah let’s keep a half-resurrected demon lord around, there’s no way that could go wrong – spoiler: it went wrong!
This is not the only thing that’s inconsistent in Diablo’s actions. Coming back to the moment where Shera’s brother, the Elven king, tries to rape her, he first brings her back to the Elven kingdom by hypnotizing her. When this happens, Diablo, who knows that she’s being hypnotized, goes to bed and cries like a little bitch instead of doing something to stop her brother. He is overpowered and knows what’s happening, he could easily beat him up and force him to release her, but he doesn’t. Why? Because the night before he had a dream about how lonely he was in his childhood. Ridiculous! I mean, if Diablo just starts acting like the average friendless otaku, there’s no point in watching the series anymore.
--- Another annoying thing in this series is the names
I already mentioned earlier that the name of the game was completely random: “Cross Reverie” – why not “Square Cauchemar” while we’re at it! A random english world and a random french that the author put one after another, probably because he thought that it would sound cool… it doesn’t you dumb fucking cretin. The names in general are random. Some sound German, like Krebskulm, some are Anglo-American like Chester Ray Galford and Greenwood, and some are french, like Celestine Baudelaire (you know, like the poet) and Emile Bichelberger. As a french person I can tell you that these names sound ridiculous, and that hearing them made by ears bleed.
--- The world-building is plain generic
There’s little development. There’s only two countries, and everything happens either in Faltra (basically the starting town of the game) and its surroundings or in the Elven kingdom. It’s a MMORPG world, so you have the usual stuff that you find in any isekai or crypto-isekai, with video game mechanics like classes, adventurer’s guild, quests, summons, levels, skills, MP and so on. Nothing new or interesting.
--- Yet again, pedophilia
Coming back to Krebskulm / Klem, she’s added to Diablo’s harem right after her resurrection, and Shera invites her to join her and Diablo in the bed, because you know, having sexual intercourse with children is cute and wholesome, apparently. And when Diablo enslaves her with a spell, he has to kiss her. She’s always nearly naked, by the way. I don’t care that she is 3000-year old or some other bullcrap, it doesn’t change the fact that she looks and acts like a child.
--- The protagonist
I won’t talk about Diablo’s personality much, as he is just your usual isekai male protagonist. It is established from the beginning of the series that he is overpowered, as his level is super high, he has overpowered equipment and skills like magic reflection, and so you know that he is going to win any fight with little to no trouble, whether it be against an army of Fallen, the ruler of the town, or the actual demon lord. He defeats most of his enemies in a matter of a dozens of seconds, one or two minutes at most, except from Krebskulm, whom he defeats with the power of friendship (gah!).
--- The other characters aren’t much better
As in any ecchi, female characters exist purely to be cute, sexy, or just a walking fetish, and as a result they are bad characters. This is the case for Shera, the elf that has huge jiggly boobs (in anime, female elf equals huge boobs if you weren’t aware), that’s her only personality trait. Ah, no, actually she’s also childish and has an irritating high-pitched voice… ugh. Her background is also pretty shit. She’s a princess who wants to be an adventurer because “blah blah blah freedom blah blah blah follow your dreams”… you get the idea. Even her dream is ridiculous: she wants to open a café with Rem and Diablo!
Then you have the cat-girl, Rem. A slightly less shit character because she has an actual objective and a better background, but she’s still mostly here to be Diablo’s plaything.
Both of these girls are too weak to fight by themselves, but thankfully for them Diablo is always here to save them.
The demon lord Krebskulm / Klem is just your average loli, she even has the moe face expressions and the chibi face at some moments. Because of her incomplete resurrection she forgot her memories and how to use her demon lord powers, and so instead of acting like an actual demon lord and killing people, she just wants to eat biscuits with Shera, with whom she sings a “biscuit song”… This is just stupid and unfunny.
The bad guys are even worse. Shera’s brother is cartoonishly evil. He is just your typical garbage anime villain that is easy to hate because he is a rapist with the generic anime psycho face and the generic evil laugh. Same thing for Saddler, the paladin of the church (or something like that, I didn’t pay much attention to the lore of this generic MMORPG world), who is also an evil psychopath with an evil smile who loves to torture and kill, but this one thinks he acts for good and claims he is god, constantly spouting nonsense about salvation and whatnot.
--- Verdict
This is a very generic series with nothing remotely good or new in the setting, the story, the characters, the animation or the music. There are only three things that aren’t completely garbage, namely: the protagonist role-playing a demon lord, the very rare comedy elements, and the ecchi elements, which are decently done, but are not good enough to make the series worth watching. While it is an easily watchable show, it belongs to the trash can.
