A lot of the plot points feel really random, like, while there is no romance or hint of romance for a good part of the book, there is suddenly a master/servant relationship. For no reason, really. Also, there is pretty much no mention of the button again after the main character uses it to power up. So, he presses it, levels up, and then... breaks it and never talks about it again. There's so much you could do with that type of training and the plot just sweeps it under the rug, only talking about the time wizard not how weird the button was or even an "oh man, if I didn't break that button I could train even more, what a bummer."
Just an okay read, overall. I would read it if you're Isekai obsessed like I am.
