There is little information on this topic, as I have for some years being trying to unearth information on the German embassy in Tokyo.
I think the lack of information is for two reasons. Firstly the very tight restrictions the Japanese imposed on the movements and activities of the Germans (especially after the Sorge spy ring was exposed) and secondly after Japan surrendered the US intelligence services I understand ransacked the embassy building and removed all the contents. They have given out very little information since.
Wenneker whilst in US captivity was interviewed by the American press and gave his views on why Japan lost the war, reasons which concur with the general historical view.
The information on the embassy itself is sketchy - about three floors above ground level, the top floor was a radio station off limits to the personnel not involved in radio work. I gather the building was damaged by the US air raids, how badly isn't clear.
''Give me a Ping and one Ping only'' - Sean Connery.