Environmental disasters often catalyze social movements advocating for change. This study examines the mobilization processes within the Japanese anti-nuclear movement following the Fukushima Daiichi nuclear disaster, triggered by the Great East Japan Earthquake and tsunami on March 11, 2011. Focusing on meso-level dynamics, which have been underexplored in social movement research, the study introduces an analytical model that incorporates elements from political process theory, network theory, and relational sociology. This model is applied to analyze the relational dynamics of two coalitional networks in Tōkyō engaged in advocacy: e-shift, which promotes nuclear phase-out and renewable energy, and SHSK (Shienhō Shimin Kaigi), advocating for the rights of those affected by radioactive contamination and evacuation. The research traces the mobilization processes of these networks through data collected in 2013 and 2014, including participant observations of movement events, semi-structured interviews with representatives, and documentary analysis. By focusing on these coalitions, the study sheds light on the intricate dynamics that drive social movements in response to environmental crises.
