That's a really stupid idea.

It's called the "Jieitai" or "Self-Defense Forces". The Jieitai already has the right to defend Japan's territorial waters, which include a significant portion of the Sea of Japan. The issue here is Article 9 of the Japanese constitution, which prohibits Japanese involvement in non-defensive wars. Unfortunately, some right-wingers want to repeal Article 9.

The Chinese and the Russians are giving the Japanese right wing exactly the behavior that can help them significantly grow the military and attack Article 9.

Their navy, for example, is the fourth largest in the world.

They only have about 60K active military members.

They may be modern, but they are no match for China or Russia.

Their navy and Air Force would dominate. Russia's military is old and falling apart. China has a huge army that would be irrelevant in a war with Japan - they can't project power. Their Air Force and navy are modernizing but most units are obsolescent. The Japanese military is state of the art across the board. Their subs are the finest in the world and they are the only other navy in the world with the Aegis anti-ballistic missile capability.

Even so, that ranks Japan about 23rd in the world in active forces. And it's only 10% of China's force.

Japan also doesn't rate nearly as high as China in firepower according to GFP.

and its land area is about 1/30 that of China's. Add the fact that Japan is an island nation with no international land border, and it has one of the world's most advanced defense systems, it should be clear that Japan doesn't need such a large force. China certainly isn't going to be stupid enough to try a marine invasion, they'd just be sitting ducks.

However, reading about what some of the wackier right-wing politicians over here (Japan) have been saying is becoming somewhat disconcerting. Like this little gem of a quote from a high-ranking official who seems to want to return to the "glory days" of 1930s Japan:

「だからそのときに、それに『従え！　それに従わなければその国における最高刑である』――死刑がある国は死刑、無期懲役なら無期懲役、懲役300年なら300年（と決まっていれば）――『そんな目に遭うくらいだったらば、出動命令に従おう』という（ようになる）」
"Therefore, when the time comes, you have to obey (orders)! If you don't obey orders, you can receive the maximum punishment in some countries. In countries with the death penalty, you are executed. In countries with lifetime imprisonment, you get life in prison. Or 300 years in prison (if it is so decided). If you are faced with such prospects, you will follow orders to go to war".

a threat. The sad thing is that it is working.