I will try to be the most direct, it will contain some text to make a review at least acceptable, it will contain some slight spoilers until chapter 5, I am using google translator so forgive my mistakes.
the writing quality is very good but the development and personality is not the best, and the story is following the cannon with gon and killua in hunter exam, not to mention the background that literally doesn't exist until the chapter I read (chapter 6) and I found 4 problems that made me give up on this story
the first being the background itself, to be more exact the MC background, the MC just has no history and starts with him in the heaven arena at 12 years old all of a sudden, maybe this will be explained in future chapters but for me, an MC that we don't even understand where he came from, where he is going, or why he is going is a big problem
second, the MC simply says yes to a man who offers to train him out of the blue after showing Nen's existence, in exchange for the MC doing him a favor, which is not made clear, and the MC in all his wisdom doesn't try to know more, the favor could be anything and the MC doesn't think about it, the MC has no sense of caution or suspicious thinking about the man who came out of nowhere and goes with him like a child (who he is) following a kidnapper who offered sweets
third, similar to his problem accepting training from the random man who became his master shortly thereafter, when he follows his master to a party due to the master having to find someone, the MC is approached by a random girl who invites the MC to accompany her somewhere because her sister wants to meet him, as smart as ever the MC accepts without thinking twice with the wise reason of having nothing to do while waiting for his master, the MC is almost killed by this girl to learn to be an idiot.
fourth, when the MC is about to be killed his master appears and saves him, the girl cries and regrets having "tested" the MC and asks his master for mercy... which is granted... even the enemy is exceptionally dumb to cause such a problem and provoke someone who shouldn't and she still survives, she has a plot armor or something?, and as if that wasn't enough as they walk away she decides she's going to chase the MC... here's the recipe for xianxia villain that will cause problems until it dies
Now think about it, the MC gets into a fight and is almost killed for a nonsensical reason like testing him in which she threatens to kill him if he doesn't complete her little game, he almost gets killed, and instead of the master of the MC kill her because she was disrespectful like she almost killed her disciple in a party he just lets her go and she still decides to cause more trouble in the future? the author also seemed to want the MC to become just like the killua with all the skills of murder, claws, etc, he even kills a guy the same way killua kills johness by ripping out his heart but for some reason, he didn't make him a zoldyck (no background or history as I said before), add all this to the previous problems and I come to the conclusion that the only thing tested in chapter five was my patience, which unfortunately is low, especially with stupid MC's