The story of Chainsaw man in DXD is by far one of the lamest ones ive seen to this date, first of all, why would you pick to be as fast as flash, when you could just use chainsaw mans chains to move faster, and he even has chainsaws on his legs, so running with them would be a pain, and couldn't you just have wished to get a harem if that was one of your main objectives, and why would you choose all knowledge of mechanics, when you could just have chosen a cooler power like making it so whenever you see something you can gain all the information you need from that object, and know exactly how it works, the development of the story goes as well as you could imagine for this type of story, the world the main character got transferred to does not feel like a new world, it just feels like he got teleported to Japan, you even had to fill a whole page with a million words just to bypass the 15k letters filter, over all, this story brought a tear to my eye.