He really is a wretched piece of shit, but he's the edgy protagonist so a certain readership will bend over backwards to defend him.
This is clearly not for me. I don't really understand why it would appeal to anyone, but oh well. Have fun with it, I guess.
With this author, I don't think there was ever a chance of this taking the 100 Girlfriends approach. I always assumed that merging the Karins would be the endgame. I do wish it had lasted longer than this though.
I did write "basically," not "completely." He has no individual identity and a flat personality. That's not a great starting point for a main character.
I think this premise would be significantly more interesting without the memory loss angle. Making the protagonist basically a blank slate rarely works out well.