This book organizes the intent and purpose of the Japanese competition law (Antimonopoly Act) to address the digitalized socio-economy and provides a detailed explanation of its basic content as well as advanced issues. It includes an overview of Japanese law and its international position, a basic understanding of the big data and AI issues in today's competition law, and perspectives on high-tech regulation. In addition, it includes a variety of important topics, ranging from exploring principles to tackle digital regulatory realities, to understanding and analyzing the competitive realities of multisided markets. It also examines the relationship between information and competition law and that between consumer and competition law. Digitalization is a key concept in our economy and society today. Carbon neutrality initiatives, the need to improve productivity, globalization, and new ways of working are all seeking breakthroughs by way of digitalization. What's more, digitalizationrequires free and fair competition in order to encourage technological innovation. The search for transparent and clear competition laws is essential to promote efficient and effective research and development and to promote public awareness through competition.