Despite a surge of studies on the construction of researcher identities among English as a Foreign Language (EFL) teachers, insufficient attention has been paid to their ongoing identity development after establishing a researcher identity. Using narrative inquiry, this study investigated how an EFL academic transitioned from being a rising star in research to becoming a teaching-focused academic midcareer with emotional flux in situated socio-institutional contexts. Data were collected from semi-structured interviews, narrative frame, institutional documents, and the participant's academic profile. The data analysis revealed that while the participant started her research journey as a confident novice researcher, she faced negative emotions arising from encounters with potential bias in academia, institutional managerial practices, and diminished self-agency with waned research motivation. Such negative emotions gradually escalated, posing severe impediments to her researcher identity. Eventually, these impediments resulted in her research stagnation and subsequent transformation of her identity into that of a teaching-focused EFL academic midcareer. The findings provide a nuanced understanding of the complexities involved in the continuous development of EFL academics' researcher identities in the changing landscape of higher education. The study also provides implications for supporting EFL teachers in constructing and maintaining a robust researcher identity to facilitate their ongoing professional development.