Despite its democratic structure, Japan's government has been dominated by a single party, the Liberal Democratic Party (LDP) since 1955. This book offers an explanation for why, even in the face of great dissatisfaction with the LDP, no opposition party has been able to offer itself as a credible challenger in Japan. Understanding such failure is important for many reasons, from its effect on Japanese economic policy to its implications for what facilitates democratic responsiveness more broadly. The principal explanations for opposition failure in Japan focus on the country's culture and electoral system.
I really like this book - I read it as part of my own research paper to understand the dominance of the LDP (and from a comparative perspective), and I'd consider it a must-read to that end. The notions of clientelism + fiscal decentralization don't quite explain everything to a degree I find satisfying, but they are useful enough that as I read deeper, I will try to fit what I learn into that framework. (The notion of "institutional protection" I think we can disregard altogether - he is employing a system newly introduced in 1993 to explain a period of dominance that began in 1955.)