Hey Smitty.
I don't know the size of your truss rod nut but I'm pretty sure it's metric and you won't be able to buy an adjustment tool from STEW-MAC that will fit it. STEW-MAC caters to the Fender-Gibson market and they don't yet supply the vintage Japanese restorer with many tools.
You will probably need to rig your own adjustment tool using a thin wall metric socket and whatever else you need to get a ratchet on that nut.
Not much help for the vintage Japanese guitar guy out there.
Good Luck