This article reports on a mixed method study that investigated the differences in Japanese EFL (English as a foreign language) learners' satisfaction toward two different online teaching formats incorporated in universities during the COVID-19 situation: synchronous online courses (n = 324) and asynchronous on-demand courses (n = 323). Applying the items of the previously developed online satisfaction scale in the literature of online learning to EFL learning contexts, this study examined learner satisfaction from three main factors, "engaged learning," "agency," and "assessment," as a quantitative inquiry. According to the Mann-Whitney U test, there were significantly higher results of "engaged learning" and "assessment" in synchronous online courses than in asynchronous ondemand courses, indicating a higher level of learner satisfaction in synchronous online courses. In addition, based on the qualitative text-mining analysis of learner comments on their perceptions of the online courses they had taken, findings suggest that synchronous online courses accounted for higher percentages of positive comments compared to those in the asynchronous on-demand courses. This study shows that synchronous online teaching ensured higher satisfaction among Japanese EFL learners than asynchronous on-demand courses.