Rei can see spirits, and so together with his beast companion Shiro (who takes the form of a human), he helps those who're being tormented by evil spirits. Though eventually he comes across a spirit that haunts him personally...
This was my first full novel in Japanese that I managed to get through. It was slow going at first, but by the end I was able to read several pages in one sitting. The story was interesting and easy to follow, and I found Rei's struggle within himself to be an interesting but tough read.