So, I've read a couple of chapters and this is really MC f*cking just one girl for 20 chapters? If so, how boring for a dojinshi, really. And it's a shame, because the art style is great.
Chapter 23 - heavy NTR bait warning. Beware! Also, it has some threesome sex and clone gang-bang stuff, so sadly it's not as vanilla romance as it may appear at first.