Previous research has demonstrated that unique names increased in Japan, which shows a rise in uniqueness-seeking and individualism. To increase the validity of the prior findings, it is important to confirm the robustness of their results. Therefore, this study examined another indicator of historical changes in names in Japan. Specifically, I investigated whether the rates of common names decreased in Japan between 2004 and 2018. The dataset used in the previous study was analyzed. The results consistently showed that the rates of common names decreased for both boys and girls for the period. These results were consistent with the previous research, which further increases the validity of the finding that Japanese culture became more individualistic.