Grotesque by Natsuo Kirino.
If you have any interest in far eastern literature you might be interested to read my book review for Natsuo Kirino's book, Grotesque. Kirino previously scored a big success with the previous book "Out".
On that page you will also find an interesting and informative video reviewing half a dozen modern Japanese books which makes good viewing.
You can read that review and see the video by clicking here.