Laying out a religious tradition simply, but with enough detail to make the reading worthwhile is difficult. H. Byron Earhart accomplishes this in his short book: Japanese Religion: Unity and Diversity. Earhart plots out the entire course of Japanese religious history, from prehistoric times to the post-world war period.
His overriding thesis is that Japanese religions, while diverse, strive for a certain level of harmony. The same can be said, generally, about Chinese religions. Certainly, the different religious traditions in Japan have had moments of friction, and there have been major cases of religious persecution. But compared to the West, the incidents are few and far between.
Earhart is a fine guide through the twists and turns on Japanese history. The third edition was written thirty years ago, so this is a flaw with the work. This book will not reflect current research, and will also fail to track Japanese religion in our time.