Final answer:
Japan and Germany fit into stage 5 of Rostow's five-stage model of economic growth, which is the age of high mass consumption.
Step-by-step explanation:
In which stage of Rostow's five-stage model of economic growth do highly-industrialized countries like Japan and Germany fit? Highly-industrialized countries such as Japan and Germany would fit into stage 5 of Rostow's model, known as the age of high mass consumption. This stage is characterized by a shift from production to service-oriented industries, and it signifies an economy that supports high levels of consumer spending, a robust service sector, and widespread production of goods.
Countries in the age of high mass consumption stage have typically completed their industrial transformation, resulting in high standards of living and small family sizes, driven by a consumer economy.