Japan was like several european countries in having a monarch in the 19th-early 20th century who developed a modern centralized state, and then having war lead to democracy in the 20th century. Then you had McArthur rule as a dictator for seven years during which time he imposed major government reforms, including land reform and welfare reform: https://en.wikipedia.org/wiki/Supreme_Commander_for_the_Alli.... After the end of occupation, a single party, LDP, held power for almost 40 years, from 1955-1993.
MacArthur was there till 1952 and was tasked with rebuilding, establishing a viable democratic government, then exiting. The majority of growth came after him.
Compare to Mao, Stalin, and other dictators of the era.
