There was "semi-regular" liner service from Germany to Japan and return - at least, until they started getting shot at in the Atlantic, Indian and Pacific Oceans... Then "service" was cut back drastically. That's how the Japanese got their radar, such as it was. They still thought their "night vision" better than radar, but radar's range did increase significantly during the war. Several other items came via ship, but since it was getting too dangerous for that mode of travel, that's when the Yanagi Missions started via I-Boat and U-Boat for the exchanges. The Italians sent several submarines also, but I do not know if any of them went on to Tokyo, or just stopped at Penang, Java or Singapore... We do perhaps have the percentage a pinch high for late '43 into '44 for those liners, but there were some. Now, what did I do with that link?... wikipedia doesn't tell you a thing about them...
was it U-Boat dot net?...
