Whoah....you may have something very special here...it’s going to need some further digging for sure. That “00” above your serial number is known as a “double zero” Toriimatsu Nambu in the Japanese collecting world. Typically found on the very early production pistols from Toriimatsu and is believed to denote a factory experimental run of a certain firing pin design which differs from normal production. They are very rare and extremely desirable. An immediate discrepancy, however, is that the double zeros typically fall into the date range of 16.10-17.2. I don’t know enough about these to know what that means for yours, but certainly worth some additional research! It’s estimated that only about 185 or so were marked that way from what I’ve read, so if you have a legit double zero Nambu you hit the jackpot.
http://www.nambuworld.com/2011-2 Double Zero.pdf
