Tsunamis are one of the most damaging natural disasters. They are often caused by seafloor displacement due to large subduction zone earthquakes. However, these large earthquakes happen relatively infrequently, so observational data is limited. Physics-based computational simulations provide synthetic data that yields insights into such systems. Tsunami Squares is a numerical method for simulating the wave propagation and inun- dations of such events. We demonstrate the performance of a new C++ port of Tsunami Squares in replicating the 2011 Great East Japan Earthquake and Tsunami. Initial seafloor uplifts are calculated using tools from the Virtual Quake earthquake simulator. We compare simulated coastal run-up and wave heights to observed inundations and NOWPHAS buoy wave observations. We find good agreement between simulation and observation.