Well, there's many reasons why Japan is still a region aside from Others and NA.
1) Because Sony and Nintendo are japanese companies, so some of their games are relocalized, which made an interesting market.
2) Handheld is very strong in Japan. DS is nearly 21 million.
3) They put it because it's a really different market that acts like no other.
If you see the trend... NA love shooters, Others love sport games, Japan love games from Japanese creators.







