I'd check out these maybe:
This is of course a classic and of interest to anons here. It's all about how the ideal samurai should conduct himself and face life, along with a lot of other interesting things throughout
>The Nobility of Failure: Tragic Heroes in the History of Japan (Ivan Morris)
I'm reading this right now, but it's great. The author was actually a friend of Yukio Mishima and wrote this partially in response to his coup-attempt. Each chapter is about a particular Japanese cultural hero, starting from mythic times with Yamato Takeru up to nearly the present with Kamikaze squadrons. In contrast to Western culture where most of our heroes are often connected with achieving their goals and victory, many of the most famous Japanese heroes are marked by their failure and young deaths in tragic circumstances, as well being driven by such sincerity and purity that they do what they do regardless of the circumstances or whether it is a lost cause. This attitude is connected with a sort of natural pessimism where life is fleeting, impermanent and full of ups and downs. Japanese aesthetics is all about this mono no aware
(pathos of things)
>Evanescence and Form (Charles Shiro Inouye)
Connected to the end of the previous paragraph, this book deals with the theme of evanescence / impermanence in Japanese culture from ancient times until today. This book was interesting to me, but it dragged a bit near the end when it started discussing postmodernism in Japan. There are lots of example poems about cherry blossoms and the fleetingness of life and how this very character of it is what makes it beautiful and sad at the same time.
>Shinto: The Kami Way
A short book which gives a basic introduction to the Shinto traditions of the Japanese.
I have some books too on Aum Shinrikyo, new religions in Japan like Kuruzumikyou and a few things on anime from a critical perspective but I don't know if you'd be interested in those. Either way I've been planning on making a Japan thread here soon if people were interested, since there's been a lot of stuff in this thread about Mishima and Japan in general