The Japs weren’t stupid.
The Germans weren't paying attention to the shift in power between the army and navy factions in Japan's military, back during the WWI and interwar periods. At one point, Japan's army was ascendant - and it wanted to secure a big chunk of Russian territory and eliminate the Russian threat on the Sea of Japan. The Russians and Chinese had some luck during two or three key land battles and the Japanese army lost ground.
With its Navy faction gaining power, Japan started formulating "Plan B" - securing the Pacific Rim to the south.
The Japs also got whupped in 1939 by some general named “Zhukov”.