This paper introduces the initial phase of the design process of a simulator about information sharing in social media for educational settings. This online tool mimics real-world social media services and provides a playful learning experience. Players evaluate online information, make decisions to share or not the information, and as a result, gain or lose followers. Students can access other players’ statistics and analyze references such as expert’s opinions to support their decision-making. Through this experience, students are expected to exercise and reflect on their online social media behavior and become smart consumers and responsible creators of online information. The preliminary findings reveal a glance of social media sharing behavior among university students in Japan and clues for measuring the learning effects and the engagement for this sort of practice. Results from this research are expected to contribute to digital media literacy education and serious game design domains.