1943 Japanese Tachometer

I hope it is ok to put this thread under Militaria, it is a device that would have been used in the testing and manufacture of many machines, and made when Japan was at war.
The peculiarity is that the language employed on the device and certificate is English, there are no Japanese characters to be seen. The dial gives the name of the company (Teclock, still in business, although their website says they were established in 1950), the town (where Teclock still is) and the units of measurement (RPM).
The back of the device gives the serial number (mirrored in the certificate) and the date (July 1943, unless I am wrong).
The case is in good condition, and gives the name of the company, and on the back says 'Made in Japan'. On the front can faintly be seen another rubber stamp like the one on the back of the certificate. No details can be made out.
There is a certificate, and it is in English too, suggesting an English language market, or that anyone who would be using such a device would speak English. The certificate has a rubber stamped number, which I guess is the inspector's code. On the back of the certificate is another rubber stamp in the same colour ink, with the Nazi Eagle and Swastika emblem and some blurry text in German. I would expect a date, but can't make it out.
Any help with the German would be most welcome, and thoughts about why it was still essentially an English language item... Also, who would be interested in taking off my hands, I have no use for tachometers...
I tested it out with my electric hand drill, which is rated at 2,000rpm. The result you can see in the image, about 1,985rpm.
P.S. I've just spotted a typo on the certificate, '... has been inspected for it is accuracy ...' instead of 'its accuracy'. Considering how exotic English language was for them, not at all surprising.

 

An interesting artifact.
Possibly advancing occupation had confiscated enemy produced items and was turned over to agencies such as this ...
https://www.archives.gov/research/guide-fed-records/groups/270.html#270.2.1
... that may be why it is new condition?

 

On the other hand, I bought it from Germany, so maybe it never fell into enemy hands (till now).

 

My guess would be that it was manufactured for export to the USA around the time of war being declared. With the outbreak of war, Germany became their only developed country export market. However, it could have been made during the war and sold to US market after war ended, and the Nazi stamp added recently to appeal to certain collectors.

 

That makes sense, and as far as the Nazi stamp is concerned, I wouldn't have a clue if it was genuine or not.

 

The 'Made In Japan' label might be due to the US Tariff Act of 1930 which required items made outside the US to be so labelled. But why would it still be put on the box two years into a war with the US?
Apart from suggesting that the makers didn't know what the label said, it supports Smallaxe's idea that it was rebadged to appeal to the market interested in Nazi memorabilia. Is adding a rubber stamp is easier than removing a paper label...