This special issue summarizes some of the findings of the first half of our international joint research between Japan, Thailand, and Vietnam. This collaborative research is based on the framework of the e-ASIA Joint Research Program (e-ASIA JRP) and lasts for three years. Rainfall-induced landslides are a common disaster in many Asian countries. Our goal is to develop a practical method for landslide susceptibility mapping so that there are fewer landslide disasters in the future. The e-ASIA JRP is an international joint initiative of public funding organizations in the East Asia Summit member countries. Based on the co-funding mechanism, support for the research teams is received from the funding organizations in their respective countries. Since 2019, the Japanese, Thai, and Vietnamese teams have been supported by the Japan Science and Technology Agency (JST), the National Science and Technology Development Agency of Thailand (NSTDA), and the Ministry of Science and Technology of Vietnam (MOST), respectively. In the first half of our project, we completed the basic steps for developing the system. In this special issue, we are proud to present some of our achievements, including studies on slope failure analysis, landslide prevention works, meteorological observations, landslide monitoring, statistical or wide-area risk evaluations, mathematical models, and flash flood control. In addition to the above, we also present other valuable research achievements that related members have provided to help ensure the achievement of our goals. In total, 20 papers are published here. We believe that our comprehensive research activities will dramatically increase future landslide disaster mitigation, especially in monsoon Asia, and will strongly augment the roadmap for achieving the global Sustainable Development Goals (SDGs) as a common desire of humanity.