Japan is geographically in a strange place, conditionally. It is a humid place, it can also get very warm or very cold on a daily basis. As seen with the Sunwolves vs Waratahs game, they do have wind. At Newlands, when you kick, you need to keep your ball low on a windy day and it seems to be a case with some stadiums in Japan as well.
I still believe SARU was negligent to postpone the bulk player base to Japan’s conditions when most other countries have already organised their base camps and played a game or two in Japan. Luckily, we did, albeit a bit late, schedule a warmup game against Japan on September 6th, but I doubt that either side will play at strength because Japan is likely to use that as a continuity test. Though we have players in the Top League, we don’t play rugby there in that season when RWC takes place.
England, Scotland and Wales, they know Japan. The USA and the island teams also know the place very well. The ‘other’ Southern Hemisphere teams will need to adapt, however, the Wallabies and All Blacks have already toured Japan.