This qualitative study explored influences that helped to shape Japanese L2 (Second language) English users' identity development. 81 Japanese undergraduates shared self-perceptions of their L2 English identity development from personal experiences, both domestically (in Japan) and internationally. The primary focus of this study was an exploration of enabling influences on Japanese L2 English identity development. A secondary focus was an exploration of constraining influences on Japanese L2 English user identity development. Findings from this study suggested that Japanese L2 English user identity development is influenced by the individual's awareness of what identity roles are accessible and available for negotiation, and what kind of learning occurs. Major influences that emerged through thematic analysis of the data indicated that "L2 English classroom-based experiences in Japan," engagement in "study abroad and volunteer abroad programs," and "overseas travel and living abroad with family" were the most commonly referred to enablers of Japanese L2 English user identity development. Additionally, "inadequate English language skills, insufficient exposure to English in daily life," and "hesitancy (and avoidance) to communicate in English" were the three most commonly referred to constraints of Japanese L2 English user identity development. [This paper was published in: "Proceedings of the International Conference on Education, Psychology, and Learning, ICEPL Summer 2018, Tokyo," 2018, pp. 17-30.]