I guess it is a question of what makes the “best soldiers”; while the Japanese typically didn’t think outside the box, they were tough - and a few held out until the 1970s in the Philippines.
They’d burn haystacks at night to signal Japan they were ready to assist with new landings whenever Japan decided to re-take the Philippines.
I was basing "best" on who produced more casualties for the other side for each casualty on their side.
There were some interesting statistics on that from WWII.
The Japanese did well, when they were up against foes they had the technological edge on, such as the Chinese.
They only did reasonably well against comparable foes.
The Germans did the best, then I believe it was the British, then the Americans, (Brits and Americans were close).
Russians did horribly. They just threw men at the problem.
It is one of the reasons they had so many casualties. Then again, they were mostly up against the Germans.
[the Japanese typically didnt think outside the box, they were tough]
Basically, they jumped the gun. Once China was safely pacified, they could have launched their big war. Instead, they looked at Hitler’s rapid gains and thought they’d better belly up to the bar before Germany overran the Soviet Union and threatened their hold on China. The Sengoku period, in which alliances were formed and repudiated once objectives were met, until one Shogun stood supreme over the whole mess, would have informed Japanese decision making:
https://en.wikipedia.org/wiki/Sengoku_period
Germany was an ally, until its borders reached the Japanese empire’s. Given the magnitude of the technological gap, a German victory over the Soviets would be disastrous for Japan, since it would marry Germany’s massive technological lead to Russia’s huge natural resources.