there isn't anything in tokyo you can't get from ehobby or wgc or local vendors in canada in terms of parts. You will be paying more probably as things imported INTO japan face very high duties and taxes that show up in their prices. You're better off getting common parts by ordering online.
I checked out a number of stores in tokyo and osaka when I was there last year and didn't see much of anything interesting that was economically smart to bring back, though depending on what stores you go to, you might see something of interest, but gearbox parts should not be a shopping priority. Lots of interesting guns, but nothing in terms of parts or accessories.
I was in one store and condor gear was almost twice the canadian retail price after exchange as an example of how expensive things can be.
Spend your money on other things while you're there. There's a lot more interesting things than airsoft. lol.
I futz with V2s, V3s and V6s. I could be wrong... but probably, most likely not, as far as I know.