Multi-Scale Simulator for the Geoenvironment (MSSG), which is a coupled non-hydrostatic atmosphere-ocean-land model, has been developed in the Earth simulator Center. Outline of MSSG is introduced and its characteristics are presented. In MSSG, Yin-Yang grid system is adopted in order to relax Courant-Friedrichs-Lewy condition on the sphere. Furthermore, the Large-Eddy Simulation model for the turbulent atmospheric boundary layer and cloud micro physics model have been adapted for ultra high resolution simulations of weather/climate system. MSSG was optimized computationally on the Earth Simulator and its dynamical core processes had attained 51.5 Tflops on the Earth Simulator. Results from preliminary validations including forecasting experiments are presented.