Are there any reasons why Japan didn't go into war after World War 2?

Japanese history: Postwar After World War II had ended, Japan was devastated. All the large cities (with the exception of Kyoto), the industries and the transportation networks were ...

http://www.japan-guide.com/e/e2124.html

Occupation of Japan - Wikipedia, the free encyclopedia At the end of World War II, Japan was occupied by the Allied Powers, ..... Douglas A. MacArthur, Supreme Commander and administrator of Japan after the war" ...
http://en.wikipedia.org/wiki/Occupation_of_Japan

World War II - Wikipedia, the free encyclopedia 2/26/07World War II, or the Second World War (often abbreviated WWII or WW2), .... On September 17, 1939, after signing an armistice with Japan, ...
http://en.wikipedia.org/wiki/World_War_II

Japan after WWII Occupation of Japan Page provides information about Japan in post WWII era, American and allied Power policy concerning its economy, Japan's reconstruction, ...
http://www.empereur.com/DOC/Japan_occup.html

Japan after World War II | Japan Traveler Japan after World War II. — James. With the atomic bombings of Hiroshima and Nagasaki on August 6th, 1945, Japan found itself surrendering to the Allied ...
http://www.japantraveler.com/japan-after-world-war-II

CHAPTER 23: World War II: The War Against Japan Japan entered World War II with limited aims and with the intention of ..... After two partially successful attempts to reinforce Biak, the Japanese ...
http://www.army.mil/cmh/books/amh/amh-23.htm

thanks :D is it okay to include Article 9 of the National Constitution of Japan?

Oh, yes. Definitely!!

There are several reasons why Japan did not go into war after World War II. Here are a few:

1. Pacifist Constitution: Following Japan's defeat in World War II, a new constitution was drafted under the guidance of the Allied forces. This constitution, known as the "Constitution of Japan" or the "Postwar Constitution," explicitly renounces war as a sovereign right of the nation and prohibits Japan from maintaining armed forces with war potential. This commitment to pacifism has been a key factor in Japan's post-war stance of avoiding military conflicts.

2. U.S.-Japan Security Alliance: After World War II, the United States occupied Japan and played a significant role in its reconstruction. In 1960, the U.S.-Japan Security Treaty was signed, which resulted in the establishment of a close security alliance between the two countries. Under this treaty, the United States provides security guarantees to Japan, which has allowed Japan to rely on the U.S. military for defense rather than developing its own military capabilities.

3. Economic Focus: In the aftermath of World War II, Japan experienced rapid economic growth and focused on rebuilding its economy. The Japanese government and society were primarily concerned with economic development rather than pursuing military adventures. This emphasis on economic prosperity has resulted in Japan becoming one of the world's leading economic powers.

4. Public Opposition to War: The trauma caused by World War II and the devastation it brought to Japan and its population left a lasting impact. Many Japanese people developed a strong aversion to war and its consequences. The horrific experiences of the war and the devastation caused by the atomic bombings of Hiroshima and Nagasaki deeply influenced public sentiment, fostering a general desire for peace and a reluctance to engage in military conflicts.

In summary, the combination of a pacifist constitution, the U.S.-Japan security alliance, a focus on economic development, and public opposition to war are some of the key reasons why Japan has not engaged in military conflicts since World War II.