You are correct, this is a series 5 Nagoya. It appears to be in good condition with correct cleaning rod. The stock looks to have been lightly sanded, can’t tell the type of finish applied. The safety is not correct for a series 5 Nagoya carbine, the large tang was on earlier Type 38 rifles from the Tokyo arsenal, before Nagoya and Kokura. All numbers should match the receiver, if the bolt doesn’t match but matches itself, it probably came from an earlier Type 38 rifle. Rifle and carbine bolts are the same so should still work correctly.

These issues may turn off hardcore collectors but if you paid $400 or less, you got a good deal. These are fun little rifles to shoot.