Interesting Photo

[Jareth]

This looks like a post war backpack but it seems to have a single shoulder strap

[DaveR]

According to Google this is the SNLF in the second incident. The soldier concerned has a Bergman Machine pistol, so I would guess that the pack is in fact a piece of late or post WWI German kit for magazines and maintenance kit.

[Jareth]

I've seen numerous photos of soldiers with SMG but this is first time I've seen such a large pouch. I don't think there's a connection to the SMG

[Type4]

The weapon is a swizzerland SIG 1920, the picture is in Shangai in 1937 the bags is the SIG bags for maintenance, i have this info from Kazunori YoshikaWa this picture is from him collection

[Jareth]

Not sure if Swiss or German THE STEYR SOLOTHURN MODEL 30 & An MP30 Steyr Solothurn. - Page 2 - Wehrmacht-Awards.com Militaria Forums & SIG 1920 1930 - Modern Firearms

[Gunny Hartmann]

Looks like the SIG M1920 to me, which is a license built MP18. They look pretty much identical

[Jareth]

Perhaps the bayonet is the clue. I think the Swiss & German SMGs used different bayonets

[Type4]

Japanese modified the weapon for put type 30 bayonet

[DaveR]

Does this help? By the way, I think the Wakizashi adds a little something.

[Jareth]

Yes note that it's a short bayonet that mounts on side. The other photo I posted has a long bayonet which isn't Japanese. The photo evidence shows the SMGs came with foreign bayonets. Most photos do not show bayonets mounted