Were the japanese at all worried about the Germans betraying them like they did with the Soviets? Same goes for the Italians, did they think the Germans would turn against them?
The Japanese and German were convenient allies, that would not step on one another's toes for such a long time that betrayal was likely not a worry for either side to consider. Both sides had end goals that intended on controlling their respective continents and continuing as allied empires. From what I know, the conflict that arose between them during WWII was concerned with ushering support for one another as distant allies.