I'm going to make this a short review. I noticed that no one actually highlighted this in the previous reviews.
The story has a gaping plot hole that kills it's fundamental premise. No spoilers here don't worry!
Riddle me this, the main character Tanya was an atheist in his past life who offended God and thus was reincarnated.
He uses science as a justification for his belief.
However:
1. He meets this so called being X before dying which is a highly non scientific manner.
2. Being X reincarnates him, yet he denies that Being X exists. Where is the logic in this?
3. Being X reincarnates him in a society where magic is normal. The society also happens to be in the past in an alternate world which indicates being X's control over pretty much everything. Where is the Science in this!
4. Given that the above occurrences fly past current human logic and science - reincarnations and magic, I mean, it would not be difficult for a main character if smart to rethink his stance of atheism. Which brings me to point 5,
5. Which is, Tanya was a sociopath in his past life only concerned with rising the ranks and living easy. I hardly think that he would give up the chance to suck up to being X and end up in a happier universe. He seems to have no issue with sucking up to humans.
6. Additionally, he's reborn as a military ace. The entire point of his reincarnation was for him to learn how to deal with strife. This becomes moot if the guy is reborn as some undefeatable paragon.
Anyways, despite all of that, he refuses to believe in the clear superiority of X, how X has given him everything he currently has for reasons unclear and is even vain enough to think that he can beat X.
Now if he can, that would be interesting. Till then, the plot makes no sense.
Dude doesn't question that he's been reborn, there's magic, he's in an alternate world. I mean.