Book excerpt: This book shows how telecom, broadcast, and Internet researchers as well as experts from Japan's leading mobile operators interpret, analyze, and evaluate the emerging phenomenon of the Japanese broadband ecosystem. The broadband ecosystem, as it rapidly changes against the backdrop of swift technological progress, is forcing major changes in the existing socioeconomic framework and generating many policy issues that require discussion. The book aims to provide a theoretical and practical framework for policymakers to address these issues from a broader perspective than has been available in the past. The topics addressed in this book cover sharing of 5G infrastructure, online platform regulation, diffusion of autonomous driving, content industry, trends and use cases of 5G, capacity development for AI, ride-hailing service, smartphone games, the right to be forgotten, and the economic value of personal information. Although this book cannot provide definitive answers to all these recently emerging and rapidly changing issues, it does provide important guidance for evidence-based discussion involving policymakers and researchers working on these issues. It is also recommended for graduate students who want to enter this challenging field of policy discussion.