This qualitative research examines the construction and negotiation of Japanese language teacher identities (LTIs) both inside and outside classrooms at public universities in the United States. In the past fifteen years, Japanese has become one of the most studied foreign languages at college level (Furman et al., 2010; Goldberg et al., 2015; Looney & Lusin, 2019), and Japanese language teachers play crucial roles in the learning journey of Japanese language learners. However, little attention has been given to Japanese LTIs and how the professional identities affect their practice in language teaching and other working contexts. Given the impact of identity on a teacher's foreign language teaching, the current study aims to address this gap and expand the current knowledge of Japanese LTIs by exploring the narratives, positionings, and identity formation of nine Japanese language teachers at various career stages from five public universities. Data were collected over eight months through Zoom interviews, class observations and recordings of instructors' meetings. Thematic analysis and positioning analysis are employed to analyze the data. Findings revealed individual and environmental factors that influence Japanese language teachers' professional identities in the workplace, including self-perceptions, beliefs, emotions and feelings, and how these personal traits interacted with surrounding contexts. This study also uncovered how teachers negotiate their identities in the social interactions with other colleagues by positioning themselves and others, particularly on three unrepresented groups: non-native Japanese language teachers, non-native Japanese instructors, and Japanese GTAs. Finally, implications for teacher education and professional development of Japanese language teachers are discussed. [The dissertation citations contained here are published with the permission of ProQuest LLC. Further reproduction is prohibited without permission. Copies of dissertations may be obtained by Telephone (800) 1-800-521-0600. Web page: http://bibliotheek.ehb.be:2222/en-US/products/dissertations/individuals.shtml.]