This study aims to explore and compare the experiences of international academics in government-funded research institutes in Korea and Japan and focuses on their integration through primary roles and contributions, reasons to stay, and the challenges they face in their academic and daily lives. Although international academics are critical human resources in academia, their experiences in northeast Asian research institutes, instead of universities, require thorough investigation. Additionally, policy initiatives and projects in these countries tend to emphasize international academics in universities instead of those in research institutes. The study conducted semi-structured interviews between October 2020 and July 2021 with 15 international academics from government-funded research institutes in Korea and Japan. We intend to illuminate their experiences outside of universities and demonstrate that a clear academic role, a (relatively) horizontal organizational culture, and systemic support are the major reasons for their decision to stay and integrate. We also highlight the challenges they face in relation to policy, language, and family issues. International academics help create an internationalized work environment, although they frequently struggle to bridge domestic and international academia. All interviewees were male academics working in the science, technology, engineering, and mathematics fields; thus, further studies are required to explore the experiences of female international academics and those working in other areas and to compare between the academic cultures of universities and research institutes in Korea and Japan.