Buying a GMT-Master II or Submariner Date in Tokyo, Japan

[acaixguard]

Greetings! I will be going to Tokyo, Japan in August. From what I've gathered, now seems like a good time to pick up a Rolex in Japan due to how weak the Yen is compared to the dollar. If that is the case, I would like to pick up a GMT-Master II (116710LN) or the Submariner date (116610), both in stainless steel with black dial & bezel. Slight preference for the GMT-Master, only because it's a tad cheaper and there isn't anything I love more about the Sub that I want to pay extra for. However, I would be perfectly happy with either.

For those who are familiar with dealers in Tokyo, are there particular dealers I should check out first? And is it beneficial to bring someone who can speak Japanese when purchasing?

As for inventory, how hard is it to find either a GMT-Master 116710LN or Submariner date in black in Tokyo? I read in another post that the GMT-Masters are hard to find, but is that the case with the Subs too? Also, are they typically going for MSRP from dealers that do have either in stock?

Thanks in advance for your help!