This comparative study examines the divergent nuclear policy responses of Japan and Germany following the Fukushima Daiichi nuclear disaster on March 11, 2011. While both countries faced significant political pressure and public anxiety after the catastrophe, their subsequent paths diverged markedly. Japan initially pursued a complete reactor shutdown but gradually reverted to a cautious nuclear restart policy, influenced by the entrenched “nuclear village” coalition, a political culture favouring consensus, and pressing energy security and economic imperatives. In contrast, Germany accelerated its pre-existing anti-nuclear trajectory by committing to a swift nuclear phase-out by 2022, driven by robust environmental activism, pluralistic governance, and a strong renewable energy agenda under the Energiewende. By utilising the frameworks of Punctuated Equilibrium Theory, Advocacy Coalition Framework, and Path Dependency, this study elucidates how institutional structures, political cultures, and historical legacies shaped distinct responses to a shared crisis. The analysis highlights that crisis-induced political pressures translate into policy outcomes differently depending on national context, institutional openness, and energy strategy priorities, offering insights relevant to energy governance and policy design in democratic societies facing complex technological risks.