When I first started this book, I had to say 'what the hell?!?!' But once you reach a certain point, it oddly makes sense though I can't say I necessarily understand everything that is going on.
The genius of this story is that it is two parallel stories that are related to each other. The jumbled surreal images eventually make sense though you have to earn it but letting go and allowing yourself to be carried away by the story. I definitely will need to reread this one after mulling over this for awhile.
I do have to say that this is not an easy novel and would caution a casual reader to pick up a different novel by Murakami if they are reading his work for the first time and are not a fan of postmodernist literature. Despite initial misgivings, I'm glad I made it through the book.
ps: I also wonder if the shadow is based on the Jungian shadow. It is the unconscious that knows something is wrong but the conscious mind wants to deny or not readily accept.