Series in one sentence:
A boy is constantly yelled at to hide away his enviable magic abilities for truly no reason.
Series in more sentences:
An overworked businessman gets hit in traffic, then reborn in a different world, inhabited by magic and monsters. His parents are killed by a demon, whereafter the baby is found and raised by a celebrated magician, Merlin.
As expected, he teaches his foster grandchild all he knows about magic, but soon finds out Shin is way stronger than is considered normal.
Had a good start, but it completely wasted its own premise. It was so painfully boring at times, I could not watch this in one sitting.
The fact the main character originates from a different world doesn't matter and only comes in the form of maybe 3 throwaway lines.
He used to work for a science textbook publisher, and it's implied this is what makes him understand certain magic spells and perform them better, but he's not a scientist himself, he was just.. what the Hell did he even do. Desktop design?
In any case, Shin is supposed to be an adult man, which the show does not keep in mind. He acted like a regular child during his childhood and is surprisingly stupid for someone who's gone through two childhoods now. It's also a bit odd to have this theoretically very old man getting love-struck by a big-boobed 15-year-old.
I think they should've kept the romance out, it was standard stuff anyway. I never saw him and the girl spend any casual time with each other, they were already in love and their interactions primarily consisted out of heavy blushing.
Throughout the series, characters kept bringing up that Shin should keep his powers a secret and he can't be used for military purposes, but both requests are completely ignored and there are no real consequences for it.
You could say that the lazy demonic villain coming back at the end is the consequence, but why does this guy even care? He already met with Shin's strength, whereafter he retreated and destroyed an entire kingdom without anyone stopping him or even thinking about Shin. He proclaimed his goal had been met and he's got nothing to do now, yet he suddenly decides to mess around with Shin again? Talking about kicking the bees nest.
I didn't like or care for Shin's role as a magic teacher, either. I wanted a more exciting endeavour for this character. Why not have him be discovered and chased around the world by power-hungry maniacs, like the show tried to warn him would happen?
He shouldn't even be able to be a teacher; the other characters always moan not to understand any of his explanations, so how did he manage to teach them at all? The anime doesn't show, his class is just suddenly good.
Speaking of the other characters, there are way too damn many in this thing. I can't stand it when shows do this. You can't have this many characters on screen and make them all interesting, and big surprise, none of them are.
The ending is left open, making this series even less appealing to give a try. It's been 4 years, its Wiki page isn't all that text-heavy, insinuating there's a lack of interest; there'll never be a season 2.