Piovesana's famous survey is republished with an additional chapter by Naoshi Yamawaki to cover the intervening years up to 1994. It continues to be the only introduction to Japanese thinkers and philosophical thought covering the period of Japan's 'modern' era.
This is the only book on this topic in English. Bold and bare, tread here only if you dare. It is unfortunate that this touches on elitism. It's one of my more expensive book purchases. I'm very proud that I managed to read (most of) it; I feel like I know something no one else knows. A spy unto an earlier time.