Ever since the reconstruction following the second World War, Japan has been a powerhouse of technology and industry. While population was already declining well before the famine and plague hit, and the rising sea level cut into the land available for Japanese to live on, the central government – a constitutional monarchy with elected representatives – survived rather well. Cynics cite a cultural tradition of respect and a preference for order and stability.
Home to the mighty Yoshihiro Corporation, among other less globally-dominant companies, Japan produces many of the high-tech devices of the new world order. It also produces a significant portion of global entertainment media.
Japan has resolved most of its historical issues with neighboring China by surviving. China, on the other hand, was reduced to wasteland by a combination of its own voracious over-industrialization with the catastrophic global climate change, famine, and plague. In theory, there are still Chinese survivors, but nobody really knows where they are. Several centers of Korean population also still exist, but no national government has stepped up to lead them; Japan’s offer was politely declined, and they remain individually autonomous.