The use of digital participation platforms has gained increasing attention in Japan as a means of enhancing communication between governments and citizens. These platforms enable participation without time and location constraints, potentially increasing diversity and inclusivity. However, knowledge regarding their effective use remains limited, particularly concerning participation trends based on demographics and posting times. This study examines citizen participation on digital platforms by analyzing participant attributes (age and gender) and participation times (days and times of posting). Using data from Kamakura City, Kisarazu City and Kashiwa-no-ha Smart City, the study identifies regional differences in participation trends. The findings reveal that posts are more frequent on weekdays and that participation patterns vary across generations. Notably, Kamakura City has a higher proportion of participants aged 60 and over, whereas Kashiwa-no-ha sees greater engagement from younger demographics. These results suggest a relationship between participant demographics and posting behavior, emphasizing the importance of adjusting information dissemination strategies accordingly. By providing insights into participation trends, this study contributes to the development of more effective digital citizen participation initiatives in local governments.