It would help if we could identify that 'Y' mark. I'll keep looking, but I'm sure it will be Japanese-related. Japanese items exported to Germany would not have a 'Made in Japan' indication in English, I think.
Whether or not goods are marked with country of origin depends greatly on when the item was made and the laws of the country to which the item was destined to be exported. Britain started the ball rolling with “The Merchandise Marks Act 1887” to prevent foreign manufacturers from falsely claiming that their goods were British-made and selling them in Britain and Europe on that pretence.
America followed suit with the McKinley Tariff Act, effective from March 1891. All goods imported to the U.S. were required to be marked in English with the country of origin… eg “Japan” (and “Nippon” was also an accepted term). In 1914 the act was amended, requiring the addition of the words "Made In…" plus the country of origin but this was not rigorously enforced until around 1921. Some exporters adopted the required wording before it became mandatory, but that was the exception rather than the rule.
Also, in August 1921 it was ruled that “Nippon” was no longer an acceptable indication and that only “Japan” could be used. There were no imports from Japan between 1941-1945, for obvious reasons, and they didn't resume until the late summer of 1947. From then, the required marking was "Occupied Japan" or "Made in Occupied Japan" until 1949, at which time it was decreed that "Occupied Japan", "Made in Occupied Japan", "Made in Japan" or just "Japan" were all acceptable. That continued until 1952 when occupation ended and the requirement switched back to "Japan" or "Made in Japan".
After the war there was continuing “anti-Japanese” sentiment to the extent that many American consumers wouldn’t buy Japanese goods and sometimes they were stigmatised as inferior. For a while, some manufacturers used adhesive foil labels to fulfil the origin marking requirements at time of import, with the advantage that the labels could be peeled off by the purchaser (or, unscrupulously, by the retailer).