The flexure profile of the Kurile trench--Hokkaido rise system has been fitted numerically to observational accuracy by an elastic, time-dependent plastic plate model. The elastic part of the constitutive relation is derived from seismology (relaxed moduli=56% of the seismic values), while the strain-rate-dependent plastic part is derived from dunite deformation data extrapolated to the appropriate loading rates. The numerical fit of the flexure profile depends on a number of parameters such as the rock flow law parameters, the temperature distribution within the lithosphere, and the state of prestress of the plate before it enters the subduction zone. Two examples of fitting, one with Kirby-Raleigh flow law parameters and one with Carter-Av¿ Lallement flow law parameters, are given. The oceanic crust is considered to be made of strong and competent rocks in the former example, and it is considered to be made of fractured rocks with negligible strength in the latter. Because the solution is nonunique, conclusions regarding the values of the individual parameters cannot be drawn from the flexture profile alone. The present calculation, however, demonstrates the consistency between the rock deformation data and the observed plate flexure profile.