The 2011 Fukushima nuclear catastrophe marked a decisive moment for civic engagement and social movements in Japan, which now may well be standing at the brink of a new era of resurgence. In this introductory chapter, we ask how and why this new wave of political contention emerged at this particular point in time. We argue that most current upsurge of activism is part of a longer trajectory, much of which has, however, been invisible during the past decades. In order to illustrate this, we give an overview of the development of social movements in post-war Japan, which has seen a protest cycle up to the 1970s driven – amongst others – by labour unions, environmental groups, and student activists. By placing these movements in their socio-economic and political context, we explain the development of post-war Japan’s civil society and the relative absence of confrontational social movements up until 2011.