This study investigated the role of the L2 motivational self system on L2 willingness to communicate (L2 WTC) by Korean EFL university and secondary students. Drawing on a purposive sampling technique and an explanatory sequential mixed methods design, quantitative data (105 university and 112 high school students) were first collected and analyzed. Then, qualitative data (one focus group discussion with nine participants and five in-depth individual interviews) were collected and analyzed to further explain quantitative findings. Results showed that high school students, who exhibited stronger "ideal L2 self" and "ought-to L2 self," had a higher level of L2 WTC inside and outside the classroom. In contrast, university students, who exhibited a stronger sense of "ideal L2 self," had a higher level of L2 WTC in both communicative settings. While high-stakes English tests still seem to shape EFL secondary students' motivational mindset ("ought-to L2 self"), this study also suggests that pedagogical supports, such as offering performance-based English tasks, cultivating one's ideal L2 self image, and encouraging production-oriented English activities in out-of-class digital environments, could enhance contemporary students' L2 WTC in test-oriented EFL countries.