With the internationalisation of higher education, many universities in non-English-speaking countries have started offering English-medium instruction (EMI) courses. In Asia, in addition to the challenges caused by instructors and local students not being L1 speakers of English, the recent study-abroad trend has added more complexity to linguistic diversity in the classroom. This study investigates the experiences of three Japanese university students who took EMI courses in Taiwan and South Korea. Using a qualitative research method based on an open-ended questionnaire and semi-structured interviews, the study explores the following research questions: (1) how do multilingual university students use translanguaging to conduct their academic learning in EMI courses? 2) how are multilingual exchange students perceived by their peers and instructors? 3) how do peers and instructors' perceptions of exchange students affect their learning in their EMI courses? By applying the concepts of translanguaging and social categorisation to analyse the data, the study offers three main findings: (1) translanguaging is an essential tool for learning; (2) translanguaging is a potential cause for marginalisation; and (3) categorising exchange students can be a potential negative influence on students' perceived success. Ideally, pedagogical translanguaging in EMI courses should involve careful consideration of students' linguistic and cultural backgrounds.