It is not news to people of this forum that the alliance between Germany and Japan was one of convenience. They had hardly acted as partners. Nevertheless, perhaps out of diplomatic necessity, military attachés were exchanged between Tokyo and Berlin. Paul Wenneker was one of them. Tried and true as a worthy
Kriegsmarine commander, Wenneker served in Tokyo, recommending an aggressive submarine campaign against American shipping between the United States and Hawaii. To much of his frustration, however, Japanese traditions never allowed the IJN's submarine arm to act effectively, believing that submarine warfare was dishonorable (interestingly, Erich Räder in German thought similarly). As a result of this belief, Japan's submarine technology never really evolved much beyond WW1-era technology until it was too late to make a difference.
More on him here:
WW2DB: Paul Wenneker
By the way, in a separate on-going thread we've been discussing the effect of naming a ship after the country's name, and examples we discussed include the Japanese battleship Yamato and the German heavy cruiser (
Panzerschiff) Deutschland/Lützow. Well, Wenneker happened to be the commanding officer of the Deutschland/Lützow between Oct 1937 and Nov 1939.