This article considers the Buschfeld-Kautzsch ‘EIF’ (External and Internal Forces) model from the perspective of the Japan context. The model was developed as an enhancement to Schneider’s Dynamic Model of Postcolonial Englishes, which is itself an enhancement of the Kachruvian World Englishes paradigm. The EIF is a flexible model that attempts to incorporate the linguistic, social, and historico-political development of English(es) in both postcolonial and non-postcolonial settings: thus addressing the main problem that variety development has heretofore not been systematically analyzed in Expanding Circle contexts. Hence our aim is to see if the EIF model can account for this development in Japan. We incorporate material and data from an eclectic range of historical and current sources. In the process, we consider the historical development of English in Japan from the Meiji Era to the present day, introduce the EIF model in some detail, and assess the usefulness of the model to help explain how English is growing and developing in Japan. The major findings of the article indicate that the EIF model is useful somewhat problematic, and only partly accounts for variety development of Japanese English. We conclude with some recommendations for improving the model through further testing, so it may become a more useful construct for identifying the process of ongoing variety development in non-postcolonial settings.