Mark Felton, in Yanagi : Underwater trade between Germany and Japan is taking quite some space to tackle the tense diplomatic relationship between Germany and Japan:

Turning to their new allies in the West, the Japanese followed the Tripartite Pact by signing the German-Japanese Military Agreement in Berlin on 18 January 1942. However, many historians who have analysed German-Japanese diplomatic and military cooperation during the Second World War have criticized much of the appearance of cooperation as window dressing. In reality, the efforts of the Germans and the Japanese to even establish a cooperative effort with clearly defined goals amounted to remarkably little. The Tripartite Pact provided for the establishment of technical commissions designed to implement strategic plans, but they met only for the sake of form, and military talks had not been staged by the time of Japan’s attack on Pearl Harbor. The joint commissions had virtually no influence over the course or aims of the German-Japanese alliance, this role being usurped by the German Foreign Minister, Joachim von Ribbentrop, and the Japanese Ambassador to Berlin, General Hiroshi Oshima. These two men could not agree on the direction the alliance should follow and their views also diverged from those of their leaders. For example, even though Japan had been defeated by the Red Army at the Battle of Halhin Gol in Mongolia between May and September 1939, and had subsequently negotiated a non-aggression treaty in 1941 with Stalin, Oshima advocated a joint German–Japanese offensive against the Soviet Union. Both the Imperial Japanese Navy, who looked to the Pacific as the arena of future conflict, and the Imperial Household Agency who advised Emperor Hirohito, opposed such a plan. Ribbentrop went even further, advocating an alliance of Germany, Japan and the Soviet Union against Great Britain, running completely contrary to the core values and war aims of Hitler and the Nazi government, which was the defeat of ‘Jewish Bolshevism’ in the East. Such was the poor state of diplomatic relations between Germany and Japan that neither side told the other very much about their military strategy and operations. Liaison conferences were held in Germany between 18 October and 5 November 1941, but the first the Germans were to hear of the Japanese attack on Pearl Harbor on 7 December was, incredibly, on the radio – reported by the BBC! The Germans had also left the Japanese largely in the dark concerning Operation Barbarossa, the invasion of the Soviet Union, which began in June 1941. This is borne out in US Army G-2 intelligence reports of the time, the American Ambassador to Tokyo reporting in a telegram to the State Department in Washington DC on 27 July 1941 that: Former Foreign Minister Matsuoka informed the Turkish Ambassador that he had cabled Ribbentrop 48 hours in advance of the Nazi attack on the Soviet asking if there were any truth in reports of such an attack and Ribbentrop replied with a categorical denial. This reflected the other level of the German-Japanese alliance – a level of distrust between the two nations, and a reflection of the distrust between Europeans and Asians at this time. The Americans, immediately prior to the unexpected Japanese assault on Hawaii, had been monitoring relations between the Germans and the Japanese, particularly on German attitudes towards the Japanese as a nation, and as a people. Brigadier General Sherman Miles, Acting Assistant Chief of Staff of the US Army’s G-2 Intelligence Department, wrote to the Army Chief of Staff on 30 July 1941 recording some startling observations. Miles noted that the American Ambassador in Tokyo had, on 23 July, pointed ‘to a trend in Japanese public and private opinion indicating that Japan is no longer a happy partner in the Tripartite Agreement’.3 The Ambassador also stated that: if the Germans run true to form they would sooner or later overshoot their mark in Japan, and that the proud and sensitive Japanese people would eventually realize the fundamental contempt and scarcely concealed arrogance of the Germans for the Yellow Race.

Felton goes on to describe the relationship in terms of the main topic of his book - trade of necessary raw materials from Asia and military technology rom Germany, where relationships are still kept very cold to say the least.

He goes on to describe a situation when the Kriegsmarine set up a u-boot base in Penang, on the west coast of Malay Peninsula - the amount of support the said base has gotten from neighbouring Japanese posts and ports was minimal, and most of the supplies including fuel and torpedoes for the Penang base had to be brought in from Europe.

While Felton's book in the end seems to be more of a bland summary of Kriegsmarine's actions in the south atlantic and indian oceans, the parts that deal with the German - Japanese relation do make it worth the read.

Sources:

Mark Felton : Yanagi, the secret underwater trade between Germany and Japan, 1941-1945 , 2005