In this study, we developed a tsunami crowd evacuation simulation system that can be operated by local governments using a game engine and open data. The purpose of this system is to visualize the evacuation behaviours of agents and obtain data for the disaster prevention planning of local governments, such as the locations of tsunami evacuation buildings and evacuation routes. The simulation results for Zushi City showed that the disaster rate increases rapidly with tsunami height and the time margin for tsunami evacuation has a significant impact on damage reduction. The locations where agents were affected revealed that there are insufficient evacuation sites, such as tsunami evacuation buildings, along inland rivers. However, Zushi City has a maximum height limit for buildings set by its landscape ordinance, so the local government and residents must work together to develop a town that balances disaster prevention and landscape.