Megathrust systems hold important clues for our understanding of long- and short-term plate boundary dynamics, and the 2011 M9 Tohoku-oki earthquake provides a data-rich case in point. Here, we show that the F-net moment tensor catalog indicates systematic changes in crustal stress in the years leading up to the M9, due to the co-seismic effect, and for the last few years due to viscous relaxation. We explore the match between imaged stress change and the perturbations that are expected from 3-D, mechanical models of the visco-elastic relaxation and afterslip effects of the M9. While these models were constructed based on geodetic and structural seismology constraints alone, they match many characteristics of the seismicity-inferred stress change. This provides additional confidence in the modeling approach, and new clues for our understanding of plate boundary dynamics for the Japan trench. The success of deterministic approaches for exploring crustal stress change also implies that joint inversions using stress from focal mechanisms and geodetic constraints may be feasible. Such future efforts should provide key insights into time-dependent seismic hazard including earthquake triggering scenarios.