This chapter examines international human resource management (IHRM) in Japanese multinational corporations, focusing on practices for managing diverse employee groups across multiple cultural and economic environments. It outlines the classification of parent country, host country, and third-country nationals and discusses the challenges of balancing local adaptation with global integration. The chapter analyzes the transfer of Japanese HR and production systems overseas, the management of expatriates, the career development of returnees, and the evolution of local talent development. Through case studies of companies like Hitachi, Toyota, and Ajinomoto, it highlights strategic reforms aimed at fostering global competitiveness and sustainable growth.