Hi Stig,
The aircraft shown, M-2, throws up a number of questions for me.I believe it is H3K1 as it is shown to have a rear gun turret which Mikesh and Abe identify as a distinguishing feature of Kawanishi built machines.
However, I do find the M-2 marking itself strange. Presumably it is something other than the unit marking as the H3K1 machines were said to have served with the Tateyama Kokutai which bore a Japanese symbol as a unit marking seen here on a line up of Mitsubishi 3MT2:
https://arawasi-wildeagles.blogspot....a-kokutai.html
Do I take it from yor reference to M-1 that you know what this signifies? also did the Short built KF actually definitely wear M-1 or is the M- a series used just during evaluation? I don't think I've seen a photo of the original KF hitherto.
Regards,
Clint