This book examines the September 2009-December 2012 administration of the DPJ from various perspectives, including policies, party governance, management, and legacy. It identifies the significance of the DPJ to Japan’s party politics, explains the reasons for its downfall, and derives crucial lessons for the future of party democracy in Japan. The contributors, a team of professional academics and a lawyer, analyse the policies and events of the DPJ administration based on their interviews with key DPJ politicians and related persons at or close to the centre of the administration. Together they elicit insights from the experiences of the DPJ government to inform the expectations of Japan’s party democracy. Explaining how the failure of the DPJ government has long-term importance for understanding Japanese politics, this book will be invaluable for students and scholars of the field.