Excessive smartphone use has caused various issues, necessitating effective solutions. In our previous research, we developed a message notification system designed to encourage users to reduce smartphone usage. This system aims to motivate behavioral changes by sending notifications based on the user’s smartphone activity. This study explores whether displaying state changes in an anthropomorphic character based on smartphone usage frequency can foster attachment to the character and encourage users to limit their smartphone use. We developed an experimental system where the character’s state dynamically changes depending on the frequency of smartphone usage, accompanied by corresponding messages. A user study was conducted to evaluate the system’s effects on character attachment, users’ awareness, and behavioral changes regarding smartphone use. While we observed some positive responses in the experimental system, statistical analysis did not provide sufficient evidence to support the effectiveness of character state changes in fostering attachment or motivating behavior change. These findings suggest the need for further investigation with methodological improvements to better understand the potential of anthropomorphic characters in addressing excessive smartphone use.