Japanese powder bag?

[mart]

I asked hubby but he was didn`t know !!  His best guess was some kind of powder charge !!  My question would be if its Japanese why the measure 9 grams is in english ??
And I take it that the white portion is open but the darker section is sewn shut?  From the arrows showing the opening something was either poured or put into or out of that piece !!  Could be for gunpowder and the dark part is a dessicant to keep the powder dry !!
Just thinking out loud !!  If it were me I would have already opened it !!

[jondar]

King - In further snooping round on this, I found a site which describes the propellant charge of those knee mortar grenades as being in a "doughnut shaped bag" in the bottom of the grenade.  This would have to be no more than 2" in diameter to fit in there.  Is there any way your bag could be described as "doughnut shaped" and is it 2" or under?  Just kind of grasping at straws here.