Not impressive stuff, here.
I mean, sure - it's isekai, so there's bound to be formulaic stuff all over, but there isn't anything noteworthy about this at all. The art itself is fine; better than average, if only just, and at least the character designs are decent. Demon Queen's human form might have unlocked a new fetish for me, but anyway.
My problem, such as it is, rests entirely with the storytelling. I'm forever lamenting plots that simply ping-pong from one showy bit of nonsense to the next, and that's all this manga does. MC is noble without cause and without purpose, constantly pulls new powers out of his lily-white ass, continually talks about how all the badass bullshittery he pulls out of said ass was just par for the course when he first lived 2000 years go (or 200, depending on how many 0s the translator and typesetter remember to put in after the 2; it ain't at all consistent!), and I have to admit that I am sick and tired of the sheer repetitious nature of all the Shocked Pikachu Faces that those surrounding him pull. I'm seriously wondering when MC is gonna whip out a Pokeball and throw it at them.
But back to my main point of contention - MC encounters antagonist, pulls off a Brand New Move, moves on. Next chapter? New baddie, new BNM, moves on. Next chapter? No credit for guessing what happens this time. The minor (so minor that it's hiding from P. Diddy) subplot of MC's original fiancee trying to kill him gets glossed over and swiftly forgotten after its (unsurprisingly) bullshit resolution.
This is what happens when your artist friend loses a bet and owes you a big favor, and you have no imagination but played a bunch of crappy JRPGs growing up and are obsessed with a powerfantasy.
The sad thing is, there are a handful of good scraps here that, if properly employed, could have been the foundation of a good or at least decent story. Shitty family relationship could be explored more, the concept of familial love as a conscious decision rather than an emotional response could be introduced, the complexities of a master/servant relationship with a former adversary could be used to plumb the depths of ambitions and understanding beyond the common tropes...even the headmaster as a secret adversary could be an interesting plotline to meander down if only the writer had the slightest shred of creativity!
Alas, there is none to be found, and so I render this with a 3.5/10, with most of that score being dedicated to the competence of the artist.