I don't like the vibe this manga is putting out. It's not malicious, but it feels dated. A girl doesn't have to be emotionally broken/cold cause she likes fucking dudes. She could just enjoy casual sex as much as other guys around her do.
It's early to tell which direction author is going to take this in, but what exactly is the message he is trying to say?
Is it "its okay to not be 'pure', someone will see you as that way eventually" or "There is no pure, just do what make you happy and don't mind what other people say"?
I see the former (which is what I am currently perceiving this manga as) as condescending . Maybe not to the Japanese, but women aren't exclusive there, so I don't think that's a valid excuse to have dated views on women's sexuality. Either way, it has the potential to be a cute romance manga between someone who is very comfortable with their sexuality and someone who doesn't know the meaning of the word.