Nazi Germany and Imperial Japan shared some similarities leading up to and during WWII. Both had strong ethno nationalist sentiment, both had massive militaries and became pseudo-military states, both had expansionist foreign policy (lebensraum/co-prosperity,) both engaged in ethnic cleansing.
Germany and Japan's entwining as Axis powers seems different from that of Italy and Germany. Obviously their geographic distance and the composition of wartime fronts kept them from fighting side by side in either theater. Also, Hitler considered the Japanese to only be "honorary" mensch.
Why were they allies?
Did they have much equipment, tech, or intelligence exchange? Did they exchange officers at any level? Did they engage in domestic diplomacy beyond being allies? Did they share food or material resources ( e.g. Japan's desperate need for oil?)
Aside from the failed Japanese campaigns in eastern Russia the Aleutian archipelago, what did Japan do for Germany and vice versa?
The Tripartite Act linked Japan, Italy, and Germany together, that if one nation declared war on them, the other nations would follow suit. Germany did this specifically to keep America out of the war in Europe, due to Japanese pressure in the Pacific. Japan did this partly to counterbalance potential Soviet moves, as they were clashing in skirmishes on the Manchurian border.
Ultimately, the alliance would draw both countries into war with contradictory strategies, because it was not a true coordinated alliance. Germany refused to tell Japan about its invasion into Russia. Japan, therefore,moved on its southern advance strategy against the US. Japan thought war against Russia would be unwinnable, especially due to the failed skirmishes along the Manchurian border, so it signed a non-aggression pact with the USSR. However, if Germany had simply told Japan, Japan could have prepared exercises to tie down USSR troops, but Germany did not trust their ally enough to do so. Those troops would go on to defend Moscow.
Japan and Germany exchanged technology, helping develop planes, aircraft carriers, and Japan's new super-heavy battleships. Japan still did not have the intellectual capital to develop many designs on its own, so it needed good relationships with nations like Germany, aka nations that had felt snubbed after WWI. Technology exchange to Japan was limited after it left the league of nations. As far as resources go, Japan was too far, and Germany too restricted, to be able to send many supplies. Moreover, they did not have the primary resource both desperately needed, oil.
The alliance was made purely out of political expediency for short term gain. Many think one of Hitler's greatest mistakes was honoring that alliance, even though the surprise attack on Pearl Harbor gave him every excuse to back out of it. They however never really coordinated with one another, like Italy and Germany did.
One note is interesting. Japan had to censor parts of Mein Kampf that would refer to or imply the Japanese are inferior. Hitler had to make special exemptions for the Japanese, referring to them as close to Aryans. Hitler wore a Kimono, and Japanese girls wore the brown Nazi uniform. Leader of the Japanese military attache in Berlin, Oshima, was considered to Nazi like for the Nazis. Oshima was dumbfounded that any German would surrender in Stalingrad, let alone Paulus.