There's no single Japanese skin pack as yet. I'd like to compile one in the future, but for now I'll just release all my Japanese skins separately -- I'll release them as soon as ECA Panel 3.0 comes out.
For the meantime, here's a list of all my Japanese skins, both those I've already released and those completed but not yet released. All will be available at Airbuddha's.
A6M2 Zero (2 skins)
G8N Rita (coming soon)
J1N1-S Irving (coming soon)
Ki-43 Oscar (coming soon)
Ki-45 Nick (coming soon)
Ki-84 Frank (coming soon)
N1K1-J George (coming soon)
There are two G4M Bettys at Airbuddha's by Emil.
There are a couple of Tonys available at Major Lee's Aerodrome: http://www.kvi.net/~majorlee/index.html
There are a couple of Zeros and a Kikka/Karyu jet fighter by Captain Manduca at http://members.xoom.com/kikegg/
That's all I know about the Japanese skins. For Allied skins, just look around at Airbuddha's, Major Lee's, Cord's, and other sites...they're out there.