I've tried to find the mangaka's age, but there's almost no information about him available.
I'm pretty sure he has to be a kid, right?
Like someone who has no idea how to construct a decent story. Or how to keep a story interesting with intrigue, pacing and character development.
The guy just shoves more and more girls into the MC's bed. And the girls are looking more and more alike.
It's like he had a simple idea, cute monster girls all fucking one guy, and started building a shitty "story" around that.
Plus, the art is getting worse and worse. Even the sex scene are "meh". Like he copied the art of his favorite hentai, but they were censored completely, and he is still a virgin... with no imagination.
TL;DR : This manga is pretty much shit, but like a train wreck, you can't really avert your gaze from it. You want sexy monster girls lusting for one guy, but with a somewhat OK story and great art, check Monster Musume.