The popular conception of the Japanese politician is that of a man (almost always), who is pushed and prodded by forces beyond his control. The structure of politics and the environment in which he operates have been the focus of most scholarship.
There are biographies, of course, but English-language studies tend to gloss over "the inner life"; instead, the individual is used to make points about bigger issues. "Shadow Shogun," Jacob Schlesinger's wonderful book about Kakuei Tanaka, for example, is a study of Japanese money politics, of which Tanaka was the finest practitioner.
Ofer Feldman, an associate professor of social psychology and politics at Naruto University of Education, has traveled a different path. He has devoted his work to political psychology. He edited and contributed to "Political Psychology in Japan" (reviewed here Nov. 9, 1999), and has followed that up with "The Japanese Political Personality," a scrutiny of the Japanese politician's psyche.