I am a Uechi Ryu practitioner and a musician. I purchased an Okinawan Sanshin from a marine after returning from Okinawa and I play it a bit.
Last week someone advertised a “Japanese Banjo” for sale.
I got it for $20. It has real snakeskin (torn on the back).
The bridge is missing, but I have an extra.
The neck is loose and I see there is a string in the gap.
Was the string used to tighten the neck joint and it came loose?
How do you tighten the neck joint?
Pictures please? Otherwise we don’t know what you mean with loose
I would say “otherwise we don’t know what you mean by Japanese Banjo” 
That too. I thought it was just me that did not understand it.
When I watch videos of somebody assembling a sanshin/Shamisen and the neck usually fits snugly
No glue
This neck is just a bit loose. I don’t want to glue it.
There is a string around it. I’m wondering if the string was to tighten up the joint somehow by making it a little bit bigger in the neck?
Looks like a very rudimentary Sanxian, with beefier lathe’d pegs, varnished neck, etc.
A bit too elongated oval of a body, to be honest.
But… What’s with the piece of a Leiqin bow there?
Did it come with it? Where’s the rest of it?
Howdy.
As the others have stated, I do not think you have a shamisen or (at least standard) sanshin here.
It looks much more like the smaller version of sanxian found to the south.
But I would like more information before making a judgement call.
In the meantime, you may find this website to be of interest.
It showcases the basic seven types of sanshin found (at least currently) in Okinawa.
Here’s another site with a blurb about four of the spiked lutes found in asia (including sanshin, shamisen, and sanxian)
