How did Japan change in the war years following world war 2?

Japan was devastated.

Explanation:

Industries and transportation networks were crippled, shortage of food and water, the Japanese war machine was completely destroyed. The emperor of Japan lost all political power. In short, the country was in ruins.

After the defeat of Japan in World War II, the United States led the Allies in the occupation and rehabilitation of the Japanese state. Between 1945 and 1952, the U. S. occupying forces, led by General Douglas A. MacArthur, enacted widespread military, political, economic, and social reforms.