Review Detail of ZST in I reincarnated in DxD without any System

I'll start this out by saying I'm not someone who's well-versed in DxD lore or fan fiction and have only read till chap 10, I just read it cuz there's nothing else to read. Now onto the review, I did somewhat enjoy it but I think the author not attaching an overpowered on as one of the tags is a mistake. Tsukasa learning Sound, Thunder, and Fire breathing to mastery in 4 years is extremely unrealistic considering that Tanjiro learned water breathing to a moderate level in 2 years with the training of an expert at water breathing. Also, learning Rokushiki even to a decent degree should be impossible for a normal human to learn because our bodies have a limit to them. You could make the argument that DxD humans have more powerful physiques but I haven't seen anything to prove that as of yet. So, in conclusion, I think it's a great fic for people who enjoy the overpowered tag but it should definitely be included as one of the tags regardless of whether he's as powerful as the other characters in DxD. Good Luck with your book Author-san :)