Anime with a good concept but with a terrible development. Many mechanics of the world presented to us are not clearly explained through the whole show as if the creator didn't want to create a proper explanation for them.
One of those mechanics are the main battle system of the show: the Archives and Themas. They explained that it is always the opposite of oneself, however it was never explained how they learn to cast their themas or how researching about their Archives and Themas might make them more powerful. They only read books and somehow are stronger?
Another mechanic that's not fully explained is how they know that oneself has ran out of magic power. They somehow just know when someone is low on magical power. Is it correlated with physical stamina? Is it some kind of aura that only magic users are able to see?
Besides that the universe seems rather small when the knowledge about magic is so big in the anime.
In this show we only get to know about the existence of two magic schools and the Iscariots... With a whole magical society to create the only things the creator is able to present us are two schools, in which one of them is completly destroyed (and the main characters don't even seem to care that much) and one antagonist group, which has a incredibly confusing motive. I mean, the Iscariots want to kill Arata because he has the a Demon Lord inside him that will destroy the world with the Trinity Seven and somehow it creates a loophole?
On top of that, every single female protagonist falls in love with the main character without any proper relationship development. The character that got closest to that was Mira but the creator only bothered to do so because she's the tsundere of the party and he couldn't just make her love Arata out of nowhere.
In addition to all the other shit I've covered, the show has a horrible pacing. The main character barely learns how to cast two spells, which one of them is used with the sole purpose of aiming the first spell or whatever the fuck that was (as said the mechanics were poorly explained) and right after that the main characters face one Lise after acumulating enough power to be a candidate to Demon Lord. I mean this could have worked but the solution they found was speed-training the protagonist a spell (or skill idk) that's not even from his Archive. I mean, they do say that the Superbia Archive "rules" over the other Archives, but they say that on a OVA that happens after the 12th episode (that's also an example of how poorly the universe is explained).
Well, those are my thoughts on this anime. I'm not an expert, an anime soummelier or anything, but I just got pissed with the waste of potential this show had. Don't plan on watching the sequels.
Thank you for giving me some time of yours to read my humble review.

Edit: I've stumbled upon this review I did and realized how poorly I've written it.
I was only mad that a universe with such a potential was wasted.
Either way, if you would like to read a review written by a more competent user here's one: