The senpai/kohai (mentor/junior) relationship is one of the core sociological features of Japanese culture, particularly in the context of education. This presentation reports on the positive effects of having three upperclassmen (senpai) volunteer as teaching assistants in a freshman online English class at a private university in Japan. Surveys and interviews indicate that having this important senpai/kohai interaction within the classroom increased learner motivation to study English, and learners’ overall performance improved.