Numerical simulation in astronomy is regarded as the third methodology of astronomy alongside observational and theoretical astronomy. We need computer simulation because it is practically impossible for us to perform laboratory experiments of astronomical phenomena due to their huge time and spatial scales. We create universes in computers (often very large ones, referred to as supercomputers) reproduce astronomical phenomena there, and observe their behavior. In other words, computers are experimental tools to create virtual universes, and at the same time telescopes to observe them. In these virtual universes, we can watch the very early stage of the cosmos and its evolution, we can reproduce the formation of galaxies, and we can witness the origin, evolution, and final fate of planetary systems including our own. Our project, CfCA, possesses various types of high-performance computers such as a massive parallel computer Cray XC30 (ATERUI), a bunch of special-purpose computers for gravitational many-body problems (GRAPE) and other facilities, all of which operate twenty-four hours a day, throughout the year. Astronomers all over the world use these resources. In addition, CfCA works on research and development for new computer hardware as well as software algorithms for the next-generation of simulation astronomy that will enable us to perform the largest numerical experiments ever attempted. By numerical simulations with supercomputers, we will, probably in the very near future, solve the longstanding questions such as the formation of galaxies, the origin of the Solar System, and the real picture of black holes.