The last 2 trips I've made to Japan were interesting in that I met local collectors of early numbered bikes and visited Yamiya and the Restore Shop. Anyways, my interest is tracking down early frame numbered bikes as many Japanese owners don't record their frame numbers in our directory. Additionally, engine numbers are generally not stated by Japanese owners.
The point of this post is to advise that Frame #5 exists and is owned by a collector in Japan. I've also been advised that Frames #1 through #4 (although still anecdotal) were not released for sale. Kawasaki on the other hand released all their single digit bikes and 8 are known to exist with frame 1 in the Kobe Maritime Museum and another in a USA museum
So far, of the 9 possible single digit bikes, 3 remain. Frames 5, 7 and 9. There may be another or two but my thoughts are that these 3 are all there is.
Just thought I would share this information