This chapter examines the intricate and contested processes through which Japan’s post-war constitution was formulated under the American-led occupation. Although Japan’s direct role in drafting the new constitution was limited, Japanese political actors proved instrumental in facilitating domestic acceptance of far-reaching occupation reforms. While the process generated significant achievements, including the establishment of democratic governance, economic revitalization, and advances toward gender equality, it simultaneously raised enduring questions concerning legitimacy, national identity, and the authenticity of constitutional reform. Critics have long debated whether a constitutional formulated under foreign occupation can genuinely reflect a nation’s sovereign will. Nonetheless, scholars such as Miyazawa (1956) argue that the transformative reforms amounted to a strategic redefinition of Japan’s international image.