Pennington and Richards (2016) argue that if the medium of instruction (MOI) is not the native language of the instructor, lack of proficiency in the MOI could bring about a lack of confidence. This study inquired how native Japanese as a Foreign Language (JFL) teachers at tertiary institutions in New Zealand and Australia perceive their English proficiency, how it influences their linguistic identity, and how the fact that they are native speakers of the target language influences their linguistic identity. Based on responses from an online questionnaire with more than 50 respondents as well as 12 follow-up individual interviews, this study argues that their linguistic identity is not narrowly conceived around their non-nativeness in English and nativeness in Japanese, but constructed from more multi-faceted aspects of language teacher identity formation, especially by factors pertinent to the very nature of the tertiary teaching environment in these countries.