Fede - I have the 7.65 Browning box in my collection, but had not seen the 6.35 mm one, although I have the cartridge. Years ago, I had about seven or eight rounds of the 6.35 mm, but they came loose in a box that turned out to be 7 mm Nambu. Those rounds long gone now.
The only Japanese 6.35 mm box I have is a Post WWII box, for the police. Women officers in Japan, at least for a time, carried the Browning Baby 6.35 mm Pistol.
There is a lot more to Japanese Pistol rounds than many think. The only caliber constantly attributed to them that I have not been able to verify by SEEING a cartridge I believed to be Japanese, is the 9 mm Browning Short - .380 Auto. I have seen a couple offered as Japanese, but they were pretty obviously Belgian unheadstamped rounds, which are common.
I am NOT saying that Japanese 9 mm Short rounds don’t exist. There has been some minor documentation eluding to them, although sometimes it is hard to tell if that means manufacture, or simply imported ammunition available.
The 8 mm Nambu in the pre-1946 form was manufactured in Japan for 40+ years so there are lots of manufacturing variations, even though all I have seen to date except the wood-bullet rounds are without headstamps. Rim thickness, square-edged rims, beveled rims, differences in the width of the extractor grooves and bevels, placement, shape and size of the stab bullet crimps or complete absence of them (rare enough that they could possibly be rounds that missed the crimping operation - I just don’t know for sure), etc., all in addition to the widely known GM and CN bullet variation.
Interesting subject - at least to me. The Post-war pistol rounds are interesting too, and for everyone we know about, there are probably dozens we don’t, since they probably have made the .45 ACP and the 9 mm Para for many, many more years than the dates we see in collections.