In the years leading up to the outbreak of World War II in Europe in 1939, there was some significant collaborative development in heavy industry between German companies and their Japanese counterparts as part of the two nation's evolving relations.
It is known that Japan and Germany signed agreements on military technological collaboration, both before the 1939 outbreak of World War II, and during the conflict.
During World War II the Japanese Navy traded a Nakajima E8N "Dave" reconnaissance seaplane (itself a multi-generational development of the Vought O2U to Germany, later seen in British markings on the German raider Orion, and some sources mention the probable dispatch of a Mitsubishi Ki-46 "Dinah", among other weapons.
In the other direction: When it came to aircraft equipment, the Japanese Army fighter Kawasaki Ki-61 Hien ("Tony") used a licence-built Daimler-Benz DB 601A engine which resulted in the Allies believing that it was either a Messerschmitt Bf 109 or an Italian Macchi C.202 Folgore until they examined captured examples.
[3] Civilian V-2 expert Heinz Schlicke was a passenger on the U-234 when it departed Kristiansand, Norway for Japan in May 1945, shortly before the war ended in Europe.
The Ho-Ru SPG with 47 mm AT cannon, resembled the German Hetzer tank destroyer combined with wheel guide pins like the T-34.
By 1944, Japan was to rely heavily on the Nippon-German Technical Exchange Agreement, obtaining manufacturing rights, intelligence, blueprints, and in some cases, actual airframes for several of Germany's new air weapons.
These included the Me 163 Komet (developed as the Mitsubishi J8M Shusui), the BMW 003 axial-flow jet engine (which was reworked to Japanese standards as the Ishikawajima Ne-20), information on the Me 262 which resulted in the Nakajima J9Y Kikka), data on the Fiesler Fi-103R series (which culminated in the development of the Kawanishi Baika), and even data on the Bachem Ba 349 Natter point-defense interceptor.