This chapter examines the institutional transformations that occurred during Japanese colonial rule in Korea, analyzing the administrative, legal, and economic structures imposed by the colonizers. It explores how Japan governed Korea as a colony, with a focus on the Government-General, the colonial administration, and the legal frameworks established during this period. The chapter also investigates core elements of the colonial economic system, including tariff and monetary policies, alongside a detailed analysis of the Land Survey Project. Often characterized in Korean history textbooks as a wholesale seizure of land, this project warrants a more nuanced evaluation of its impact on land ownership and taxation systems. Moreover, many institutional changes introduced during the colonial period persisted after liberation and continue to influence modern Korea. This period thus provides critical insights into the historical foundations of Korea’s contemporary systems.