In October 2019, Typhoon Hagibis struck wide areas of Japan, including the Abukuma River Basin and caused a serious flood disaster. Four months later, based on the challenges of the disaster, relevant national and local authorities have agreed to carry out an integrated flood management (IFM) project, towards enhanced flood protection, "no one left behind" evacuation, and less socio-economic damage. The authors provide a brief report on the disaster with the preparedness and on this project with its consensus-making process, and then discuss the role of pre-disaster discussions on preparedness on consensus-making of IFM, in addition to their primary function.