I had read
Asleep, which was very good, but
N.P. is more immature. It has in commun with Asleep a dreamy atmosphere, but in N.P. this atmosphere is more contrived. The novel is made mostly of scenes that take place in enclosed spaces--dialogues between the protagonists. This is a good premise, as far as I am concerned, but the problem is that the novel doesn't live up to its premise. One has the feeling that we are supposed to be fascinated with the characters and their incestuous relationships in the same way that the narrator is. We are told over and over how "weird" the characters are, and how uncanny "this all seems," but the fact is that the characters are far too normal. The descriptions of the hot summer are the best part.
A serious problem with this novel is the translation. In places, the translation is very awkward, and it's hard to tell how much of the blame should go to the translator, and how much to the author.
I can see why the author is such a sensation in Japan--there is an undeniable talent in these pages. She walks a fine line between serious art and pop culture, but in the end she is closer to the latter.