Easily one of the best anime I have ever seen. Nice story, good battles and martial style implementation, good jokes. Some times it kinda cringe but something tells me that's deliberately done.
It's about a boy who wanted to break past the limits of his body, ends up dying ans getting reincarnated(but it's not quite like other isekai animes), who makes a story to put up a facade to be this mysterious dark people but the story ends up being the actual case. It goes on to say how this timid, weak, mod looking kid is actually a master at martial arts and sword play and who he is actually living a double life.
Like I said before, the story is lit and it has good implementations and almost zero lag. Nice overwhelming fight scenes and mind-blowing acts that he do throughout the series, we get to see new things every episode and more and more info is revealed abt the character