It is written in an entertaining enough way, but the MC’s behavior is often weird and doesn’t make sense when you consider that he was 18 before reincarnating. My main issue is a bit further on. Stop now if you want to avoid spoilers. His dark magic teacher decides to put a slave collar on him and have him do manual labor for her, while spending nights torturing him with dark magic to build resistance. After of a year of this she also trains him with a spear. Compared to all of his other teachers, who asked consent, and actually taught him properly, he is most grateful to her! On top of that, he feels guilty for being mad at her for the enslavement. I was willing to give it a chance at first but that was the final straw.