Are you asking me out on a date? I am married but a nice meal and a glass of wine and who knows where it may lead.
To correct your statement you made that the technology exhange between Germany and Japan started in WW1,
at that time Germany and Japan were at war with eachother, and had been in opposite alliances since 1900. However I have
no idea if that was your little clever joke as you dont seem to be behaving particuarly seriously.
Yes you may read the documents detailing the discussions between Germany and Japan in aero engines in 1937 here:
Imperial War Museum Archives, GDC-Collection, GDC-11/381 — "RLM Misc Reports on DB600", 1937/38/39
{the particular letter is headed "9. Juli 1938 Betrifft" although the discussions elsewhere in the RLM file begin a over year before that}
Daimler actually agreed to "donate" half of all payments from Japan to the Reich, so this was with full Govt knowledge, involvement and approval.
Germany was very interested in Japan contributing in reciprocation, but principally to secure supplies of Tungsten. It would be a mistake to imagine
that Japan did not have any techological knowledge that was ahead of European practise. They did a lot of VERY clever work with synthetic aviation fuel
manufacture, which the US investigators to Japan after WW2 concluded had been very underestimated in sophistication (US Naval Mission to Japan, Report X-38(N)-1)
Foreign Documents: GDC Collection