This dissertation studies Japanese script reform in the early twentieth century from economic and global historical perspectives and sheds new light on the history of the relationships among script, business, and the Japanese empire. Specifically, it examines the campaigns of the Kanamoji Association (Kanamoji-kai) in not only Japan but also East and Southeast Asia, the Pacific, and Latin America from its foundation in 1920 to Japan's defeat in the Second World War. By exploring the intersection between the history of language and economic history and employing a variety of economic historical themes such as the history of international economic policy, business history, the history of economic thought, and global economic history, this study offers fresh perspectives on various aspects of the history of the Japanese empire, including the histories of Japanese colonies, emigrant communities, and people with disabilities. Through the analysis of newspaper articles, correspondence, and other archival sources found in various areas of the world, this dissertation identifies three ways in which script, the Japanese empire, and business intertwined in the early twentieth century: First, script was seen as a tool to enhance business efficiency by firms operating within and outside of Japan. Second, script reformers developed campaign strategies that focused on mass popularity and the urban economy. Third, and most importantly, script reformers conducted campaigns in many parts of the world in response to the changing global economic contexts surrounding the interwar and wartime Japanese empire, especially regarding finance, trade, and migration. Based on these findings, this dissertation presents a new narrative in which the history of language and economic history are methodologically inseparable, proposing a new role for Japanese history in global historiography.