A place, somewhere, that bears a strong resemblance in history and environment to Japan. Its return to prosperity after defeat in war is due to a certain law, a pillar of the state. This is the Special Law for the Maintenance of National Prosperity. 24 hours before this capsule is to bring about death, an official of the Ministry of Health and Welfare brings a letter announcing impending death, an ikigami. Those who receive this ikigami letter have 24 hours of absolute freedom to do anything and everything they want. Kengo Fujimoto has made his way through university and taken a job with the Ministry. His work now is delivering these ikigami letters.