The very existence of the new state of Manchukuo was contested throughout the 1930s. Despite its colonial reality, its form as a nation-state necessitated an attempt to generate legitimacy, and its best hope lay in performance legitimacy as a modernizing and developmental state delivering public goods and offering honest and efficient government. Less than a year after its establishment, the new state faced a crisis caused by large-scale floods in the north of the region. This article examines how it attempted to build performance legitimacy even in a quasi-colonial situation by establishing institutions and raising funds to mount a relief effort, providing food, shelter, and medical care, and in the longer term restoring state capacity by maintaining order, reopening communications, and instituting flood prevention measures. At the same time, it generated a narrative that linked that effort to its broader ideological claims to legitimacy.