Compared with Japan, the United States national debt is a mere $17 trillion or so. But if you convert that number into yen, it comes to about 1.6 quadrillion.
We laugh at children when they talk about bazillions and gazillions but a quadrillion is no laughing matter. Measuring any currency in quadrillions brings to mind the many hyperinflations seen in the 20th and 21st centuries. For example, the powerful and very wealthy Germany in the early 1920s and wealthy Zimbabwe, the breadbasket of Africa in 2008.
Japan's soaring national debt is already more than twice the size of its economy.