Since the Fukushima nuclear accident, dozens of citizen radiation measuring organizations (CRMOs) continue to observe the nuclear fallout in Japan. Their activities intersect on a regular basis with those of the Japanese government. Recognizing the different policy levels involved in radiation measuring, this paper studies the relations between local governments and CRMOs. We examine how civic and governmental infrastructures initiated in the wake of the Fukushima accident (dis)engage with each other. We link these infrastructures with pre- and post-Fukushima socio-technical imaginaries. By doing so, we explore whether and how CRMOs challenge and reconfigure political culture in post-Fukushima Japan. We conclude that CRMOs and local governments have established themselves as separate infrastructures, living and operating in the same environment, yet apart in the majority of cases. We identify obstacles and opportunities for citizen engagement in the emergency and recovery process after a nuclear accident, and contextualize CRMOs within citizen mobilization after Fukushima. Document analysis, fieldwork, and interviews with CRMOs, local governments, and the Fukushima prefectural government make up the basis of our study.