MaaS (mobility as a service) and smart transportation are key topic for sustainable societies. Multi-agent social simulation (MASS) is a core technology to solve complicated social issues like designing public transportation. In this talk, I like to present a successful application of MASS to design and evaluate taxi-sharing service called SAVS (smart access vehicle service). The service is widely operated more than 50 places in Japan by MiraiShare, a venture company established by professors that work on MASS researches. This talk also mention about the wide possibility of MASS researches to solve various social issues.