I like the idea, I eventually lost interest in the manga because it was basically one big blue-balling story. Despite the supposed ban on interspecies relations, later chapters made it transparently obvious that man are screwing monster girls all over the place, so Kimihito basically spending the entire series doing his best to AVOID getting laid by the gorgeous lusty monstergirls who adore him was honestly pathetic. Sure, lots of hot monstergirl fanservice, but at that point you might as well just go read monstergirl hentai manga instead. About the only thing that made it worth reading was the humour, and that wasn't quite enough for me any more.
That's WORSE. Using fan art means inconsistant art styles where characters look different from one scene to the next. You can see it right there in the preview images: the first shot of Miia is one of the coloured pages from the manga, the second one is fan art, and the third is a screenshot of the anime. Commission a single artist to do your art, learn to draw, or at the very least learn to use AI competently, but scavenging art from here and there to put your game together just makes you look third-rate (and depending on whose art you use and how you get it, possibly like a thief).