I've always been interested in that part of history but know very little about it, especially pre-Western contact. I was looking for some good books and documentaries that give a good introduction, somewhere to get started and get background infomation before I look into the more serious academic stuff.
If you really are interested in studying Pre-Perry Japan. Your best off starting with China. Japan was really a back water in east Asia. Getting a general rundown of Chinese history will prepare you for Japanese history better.
Japan directly imported lots of Chinese culture especially during the Nara period which coincides with the Tang dynasty in china. The art and the architecture was lifted directly from Tang dynasty examples then over time given a bit of Japanese flare. I got my degree in Japanese history and even spent 2 years in Japan studying, and I cannot stress enough how important China was to Japan until about the Toyotomi shogunate.
But to answer your actual question, look for books by Stephen Turnbull. They are easy reading and primarily focusing on military history. I am assuming that's what your looking for.