This study aimed to explore factors affecting the effectiveness of untact classes using virtual communication platforms during the COVID-19 pandemic. In this study, class effectiveness is operationally defined as the degree to which untact classes feel the same as face-to-face classes. To investigate the determinants of the effectiveness of untact classes, we tested the effects of learners’ traits, including communication competence and usage habits of social network services, and their emotional experience of numbness during class hours. In addition, the degree to which a learner perceives the relationship with a professor and other students the same as that in the face-to-face classes was measured. The results of a structural equation modeling analysis revealed that communication competence was positively related to the perceived effectiveness of classes, mediated by numbness and the perceived quality of the relationship with professors and students. This study showed that an effective operation of untact classes, which are recognized as the future paradigm in education, requires more detailed consideration of learners as well as the learning environment.