Ah, I see!
Cedric, that’s a sanshin (三線)! It’s a precursor to the shamisen originating in Okinawa and also found on the Amami islands. Hence the tropical print on the artificial skin!
It’s usually played quite differently from the shamisen we have here on Honshu.
Look up some Okinawan or Amami folk songs to get an idea of its background.
Alternatively, modern bands like BEGIN use it too!