This chapter reviews media theory from the 1980s to the 2010s, suggesting a return to a consideration of theories of mediation—this time in the contemporary moment, and in relation to questions of social change. Focusing on the “lost decades” and the sense of crisis that began in the 1990s and gained a new sense of urgency with the meltdown at the Fukushima Daiichi reactor, the chapter follows especially the work of Azuma Hiroki. It detects shifts in the way Azuma and his group deal with the problem of mediation and suggests that these shifts are closely tied to the manner in which media technology and social change are thought together. At the same time, it tracks the role of media theory as an indicator of social change, demonstrating how the presuppositions underlying media theory have transformed from the economic boom time of the 1980s to recessionary, post-Fukushima Japan.