We get a lot of Naoya's internal conflict, and even of Inuko's, but not as much of Amane's. Even if she was subtle about it, it's still seems like a pretty clear message that she likes him romantically and doesn't consider their sibling-hood to be a major barrier.
I guess on pages 5-6 she thinks that he probably likes her when he doesn't let go of her? Or would that have the opposite effect (he isn't bothered because he seems her as a sister)?