Frankly, I don't think I can ever get sick of talking about Yang Kyoungjong, the Korean that was essentially conscripted into the Imperial Japanese Army, was captured by the Soviets at Nomohan and sent to fight the Germans, was captured by the Germans and sent to the Atlantic Wall as part of an "Asian" Osttruppen unit, and finally captured by some very confused Americans during D-Day.

There was also some naval interaction as well. The auxiliary cruiser Thor was sent to the Pacific to raid shipping, based out of Japanese-occupied Singapore. There were several attempts for subs to cross the oceans to share technology, information, military advisers, and raw materials/gold, although many of them were sunk on route. A few made it, though, such as U-511, which was promptly sold to the Japanese upon arrival.

I don't know of a specific agreement between Japan and Germany similar to America's lend-lease program between America, Britain, and later, the Soviet Union, but the Germans definitely traded with the Japanese and shipped them important military supplies.

Because of the Allies' powerful navy, Germany had to ship these supplies using U-boats. An example of a German submarine carrying military supplies is U-864, which was carrying 1,500 short tons of mercury and was sunk by a British submarine off the coast of Norway. Another example is U-234, which was taking yellowcake Uranium to Japan and surrendered to the US after they learned of Germany's unconditional surrender. The supplies, especially the mercury, was vital for making explosives.

In addition to trading supplies, Japan and Germany also traded technology. On U-234, the passengers included Japanese submarine and aircraft engineers. There was also a slight culture exchange as Japanese were deemed honorary Aryans by Hitler.

I don't have a source, but I remember that when Britain was trying to capture Madagascar (under vichy control) the Japanese sent subs to sink their transports-was the only direct military cooperation in the war, the distances involved were just too big, coupled with the fact that the British navy dominated the indian ocean