Multi-Scale Simulator for the Geo environment (MSSG), which is a coupled non-hydrostatic atmosphere-ocean-land model, has been developed in the Earth simulator Center. Out line of MSSG is introduced and characteristics are presented. Computational performance analysis has been performed on the Earth Simulator. As the results of optimization, ultra high performance with MSSG achieved. Its computational performance on the Earth Simulator attained 52-55% of theoretical peak performance. In addition, results from preliminary validations including forecasting experiments are presented.