Nature of the alliance between Japan and Germany in WW2

[PanzerJaeger]

It's pretty much the way PanzerJaeger described except that the German invasion of the SU came as a complete shock and surprise to the Japanese, and one which they very upset about.

Not exactly. The Japanese leadership were angered because they were not provided the exact date and time of the attack. IIRC, Prime Minister Konoe felt betrayed because the Germans did not trust them enough to warn them ahead of time.

However, Berlin made it well known to the Japanese that the Germans were going to attack the Soviet Union. Hitler courted the Japanese for nearly a year before the invasion, hoping to get a commitment. In reaction to that knowledge, there was a major strategic disagreement between the army, which wanted to pursue the Hokushin strategy of a combined attack against the Soviet Union with Germany, and the navy, which fought to keep the southern Nanshin doctrine. As I mentioned before, the southern strategy prevailed.