This study investigated how personal characteristics such as generalized trust, self-consciousness and friendship, and desire for self-presentation are related to the subjective well-being of university students who use Twitter in Japan, including the effects of their online communication skills. We conducted a survey in May 2021 with Twitter users and analyzed their log data between January 2019 and June 2021. The log data of 501 Twitter users, including the number of public tweets, retweets, and emotional expressions among different patterns of social media (e.g., Twitter only, Twitter + Instagram, Twitter + LINE + Instagram, etc.) and academic standings, were analyzed using ANOVA and stepwise regression analyses. The results showed that the number of tweets and retweets, with and without photos/videos, increased in 2020 and 2021 compared to 2019, and the ratio of positive sentences remained almost the same for the two-and-a-half-year period of this study. However, the proportion of negative sentences increased slightly. It is clear that the factors which affected the university students’ subjective well-being differed depending on the respective patterns of social media use.