No idea if any of this helps...
http://www.infoplease.com/ipa/A0004395.html
"Death rate:
9.16 deaths/1,000 population (2006 est.)"
Pertaining to FIREARM deaths...I can't find anything. It's going to be a very small number in Japan. You may need to just give the percentage/ratio and say the actual number is not calatouged, or at least not available on the internet.