It was the time, health, and freedom needed to decide how to spend one’s life.… In the spring of 2032, the city of Yokohama became the first major municipality in Japan to publish what economists called a “Comprehensive Well-Being Ledger.” For over a century, governments had measured prosperity primarily through indicators such as GDP, productivity growth, labor participation, and household income. Yet by the late 2020s, researchers across the fields of public health, behavioral economics, and occupational medicine had accumulated overwhelming evidence that income alone failed to predict life satisfaction. A person could earn twice as much as another and still report lower happiness, poorer health, weaker social relationships, and greater anxiety. The new ledger attempted to quantify something that had always been difficult to measure: the value of time itself. Among those watching the experiment closely were two childhood friends, Kenji and Naoki. Kenji had ...