Japan is not a pacifist nation. They have a well-funded and trained "self-defense force". If attacked directly, they have the ability to engage in full-scale military operations – war – to defend themselves. What their constitution forbids is the use of war beyond their borders to achieve the state's political aims.
Under the hypocritical post-war order of the "Atlantic Charter" and "United Nations", no nation is technically permitted to engage in war aggressively to pursue national interests. If Japan once again permitted itself to go to war, it would be theoretically for defense. For instance, maybe China is being aggressive against Vietnam's sea claims. This, as a threat to Japan and allies' "regional security", would represent an occasion for Japan to aggressively project military force far from Japan's waters.
The Japanese believe that theirs is a nation committed to peace. However, I have another perspective I'd like them to confront. I'm not sure that their claimed love of pacifism is completely sincere. If they change their constitution so that they can now act as full junior partner in aggressively pushing US hegemonic interests, then what are they?
I say: nothing but a pathetic nation of losers, who lost a war big time, cowardly surrendered, and even now are subservient to American interest.
There are a few jokes in Japan concerning this. "When America sneezes, five months later Japan gets the flu." And, "As soon as a new Prime Minister is appointed, the first thing he does is call the President of the United States, even before the Emperor." And, "The Prime Minister is America's little dog."
In 1868, Japan's Emperor began the government which replaced that of the Shogun, ending the era of the Samurai. 77 years later, MacArthur sailed in Tokyo Bay to accept that government's surrender. 77 years from 1945 is 2022, just 5 years from now. Japan faces the possibility of having lived longer under the thumb of America than it ever had independence in the post-Samurai era.
Japan has been an important base of operations for US war activities throughout the Pacific region. This includes the millions killed Korea and Vietnam, but also the activities of the NSA today. Japan is paying money to help build US bases which are then used by the NSA to spy on Japanese people – could there be any spying on Japanese corporations?