This study investigates how university students in Japan employ their linguistic resources in English as a Foreign Language (EFL) classrooms and the impact on their translingual identities. Translingualism in this context refers to the practice of using a diverse linguistic repertoire, including one’s first language (L1). Despite the global shift towards linguistic diversity, EFL education in Japan often adheres to monolingual norms, potentially fostering native speakerism, which limits the development of multilingual identities. In response to these challenges, this research explores how students navigate such environments and how their engagement in translingual practices influences their identity construction. Data were collected from 120 students via questionnaires and narrative interviews with 20 of them. These data underwent thematic analysis, with additional insights derived from a multilayered framework of social activity. The findings suggest that embracing multilingualism could serve as a pedagogically enriching resource rather than an obstructive hindrance, contesting the entrenched discouragement against the use of students’ L1 Japanese in EFL settings. By offering a nuanced understanding of translingual practices among Japanese university students, this research contributes to the burgeoning discourse on multilingualism in language education. Consequently, it calls for a reconsideration of monolingual to multilingual pedagogical approaches in Japanese EFL contexts, thereby promoting a more inclusive and diversified language-learning environment.