Great start story and I recommend not abusing the period before the start of the canon so that you understand me before momonga arrived in the new world what I mean is like 50 chapters only of that part I know that the above is exaggerated but it is only an example.
only issues are some small grammar stuff, when ppl write Tanya novels the biggest issue I see is getting into their mentality and it seems you got that down, cant wait for more