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. This book offers a new interpretation, arguing that a far more plausible explanation rests on the predominance in Japan of clientelism, combined with a centralized government structure and electoral protection for groups that benefit from clientelism. While the central case in the book is Japan, the analysis is also comparative and applies the framework cross-nationally.