Real-Scale Social Simulation (RSSS) aims to simulate a virtualized real society which is developed in a cyber space as a digital-twin. We develop techniques to realize RSSSs using Large-Scale Computer Systems and to synthesize "Synthetic Societal Data" that consists of synthetic population with households information and basic activity data. Furthermore we develop a platform for RSSS such as human decision-making model, activity model, data-mining techniques from massive simulation results, and communication techniques to install acquired scenarios to real communities.