What brand post characteristics increase consumer engagement activities (e.g., the number of likes, shares, replies, etc.) on social media? Although many scholars have empirically investigated this issue by conducting content analysis of brand posts on a variety of social media, many of them targeted Facebook as the subject of their study. In addition, the study of brand posts in the context of Japan has received little academic attention. Therefore, this study attempts to contribute to the research stream by conducting an empirical investigation into the key factors that increase the engagement of brand posts on Twitter in Japan. 500 brand tweets published by SHARP, a Japanese electronics manufacturer, were collected during the months of May and August 2021. The factors were examined under a new conceptual framework that extends previous studies. The tweets were coded according to an elaborated coding scheme and analyzed using a Poisson regression model. The results indicate that entertaining content and medium interactivity (i.e., call to action) are the determinants to increase engagement of brand tweets, as suggested by previous studies. The results of this study demonstrated that brand account personality as a design element is a key determinant to increase engagement of brand tweets.