Abstract: This paper aims to (1) evaluate the disaster mitigation effects of improvement projects in a certain area and (2) provide a basis for strategic planning to promote further improvements. Specifically, we decompose local improvements in the analyzed area into multiple scenarios and examine their effects and issues. First, we describe the “large earthquake disaster simulator,” which estimates property damage and human casualties in a large earthquake. Then, the Kyojima area of Sumida-Ku, Tokyo, is selected as the analyzed area. We decompose the improvement projects implemented during 2006 – 2016 and prepare six scenarios. Finally, a simulation analysis is conducted. We demonstrate that fire spread could be effectively blocked by (1) ensuring sufficient road width and (2) identifying the critical buildings in terms of fire spread mitigation and making them fireproof.