You could say that they had been milking the whole Asia before the WWII (just like what the British Empire did), but it's been over 70 years after the war ended. But they have remained strong and likely became even stronger. What's the cause of that? As an aside, the Soviet Union had defeated Japan (twice) in local clashes even before Japan attacked the US in Pearl-Harbor. If there had been a full-fledged war between just the Soviet Union and Japan alone back then, the latter would be crushed within months. Likewise, today Japanese military is virtually non-existent but it is due to their loss in the WWII (remember they still lost that war)
Apart from limited influence in Korea and Manchuria, Japan didn't had much dominance over the rest of Asia.
Somewhere I read that the Japanese military is even stronger than the Chinese PLA. I believe they would rank among the top 5 armed forces in the world, unlike the other US allies such as Germany and the UK
You must have read it from me actually
There were some discussions on this matter springing up here and there a few years ago when someone started to claim that Chinese military is one of the strongest. I challenged that point by arguing that while the Chinese army might be greater in numbers than any other army in the world, the Chinese folks are not good fighters overall (despite all their "Sun Tzu"). There is nothing wrong with that since only a few nations still cut it as good warriors, and Japanese is one of them. So if they were given such an opportunity (though this is not possible since Japan is still basically an occupied territory), they would conquer China again. There were some minor armed clashes between China and the Soviet Union over border disputes in the late 1960s, and they all ended with miserable defeat of the Chinese military (despite their heavy outnumbering)