Purpose: This study examines the influence of cultural adaptation and succession planning on organizational sustainability at PT Mitsubishi Electric Automotive Indonesia (MEAI), a Japanese multinational subsidiary, focusing on leadership continuity, knowledge transfer, and talent retention amid frequent expatriate rotations and cross-cultural work practices. Research Methodology: A qualitative case study approach was used. Data were collected from six key informants, including senior managers and high-potential employees, through in-depth interviews, open-ended questionnaires, observations, and analyses of documents. The data were analyzed using thematic analysis with NVivo 12 to ensure the rigor and traceability of the analysis. Results: The findings show that short expatriate assignments limit effective knowledge transfer, while the dominance of expatriates in strategic roles creates a glass ceiling that reduces local talent commitment to the organization. Tensions arise between Japanese seniority-based practices and local merit-based expectations in the UAE. Cultural intelligence is a key mechanism for aligning global corporate values with local succession needs. Conclusions: To improve leadership continuity and talent retention, MEAI should adopt an integrated globalization strategy, including reverse mentoring, longer expatriate tenures, and dual career pathways. Aligning succession planning with inclusive cultural adaptation is crucial for sustaining the performance of multinational subsidiaries. Limitations: This study focuses on a single Japanese multinational subsidiary and is limited by its small sample size and reliance on self-reported data. Contribution: This research provides practical insights into succession planning and cultural adaptation, enhancing the understanding of leadership sustainability in culturally diverse multinational contexts.