Final answer:
The political structure of Japan changed to a constitutional monarchy during the US postwar occupation, featuring a new constitution that democratized and demilitarized the nation while establishing a solid foundation for economic growth and allied relations with the United States.
Step-by-step explanation:
The political structure of Japan underwent significant changes due to the postwar occupation by the United States, shifting to a constitutional monarchy. During the occupation from 1945 to 1952, General Douglas MacArthur and his team helped draft a new constitution for Japan which democratized the nation's political system. This MacArthur Constitution led to the establishment of a democratically-elected parliamentary government under the existing Emperor, Hirohito, which marked a departure from the pre-war imperial rule of Japan.
The new constitution included profound changes such as the dismantling of military power, establishing women's suffrage, and laying the foundation for Japan to become an ally of the United States. These reforms aimed at demilitarization, democratization, and fostering respect for fundamental human rights were further embedded by Japan's economic reconstruction, aided by the United States, which saw Japan emerge as a strong economic power with a public-private economic model.