This original book systematically examines Japan's defense engagement with its strategic partners since the end of the Cold War based on Japan's national security strategy. Through the ten carefully selected cases of strategic partners: Australia, India, Indonesia, Vietnam, the Philippines, ASEAN, the UK, France, NATO, and the EU, the book follows a structured, cross-case comparison based on the analytical framework developed for the research. It also discusses the evolution of Japan’s postwar defense policy, providing a solid background for the case studies.