Would also like to point out that beside Tokyo being featured in TAR15, meaning some of the teams present would have some advantage having been there, Osaka was also featured as leg 10 in TAR12 (So Ron and Chris did race there, but Kynt and Vyxxin didn't ).
As speculation, I traveled to Okinawa a few years ago, although not a large place, still is one of the last remaining places in Asia with large presence of US bases. Considering that Guam (before the US bases were disbanded) was featured in TAR11, I wouldn't be surprised if Okinawa was now the setting for a leg in a race featuring past racers.