>>51074352No they aren't.
>>51074299This falls apart when you consider that Alola and Unova are the same country, and being on separate landmasses shouldn't make a difference. Hokkaido and Kyushu are separate landmasses from the rest of Japan. You might think this explains Hoenn and Sinnoh being 100+ and 200+, and that the rest of the region would be 1+, but the separate landmass of Shikoku partially exists in Gen II as Cianwood City, and HGSS expanded upon it enough to give it numbered routes of 47 and 48 instead of 300+.
>>51074250Only northern Chubu. Gen I and II actually begin in southern Chubu (Pallet Town and New Bark Town) and end in Chubu (Pokémon League and Mt. Silver both being Mt. Fuji). Pewter City and Blackthorn City are mountain towns encroaching the mountain on each side (FRLG unfortunately omits the mountain graphics). You're supposed to be a kid who begins from nothing but rises to the pinnacle of Mt. Fuji for your final battles, with both Gen I and II protagonists meeting each other there. Kansai is pretty amply represented as everything between Cherrygrove and Olivine.
Unfortunately you're unlikely to get another Japanese region outside of remakes of existing ones. The four regions we do have exist because they're the four regions that represent the four cardinal directions on Japan. The original names for the towns representing these regions in the original GS are West (Kansai/Johto), South (Kyushu/Hoenn), and North (Hokkaido/Sinnoh). That's the order you visit them in-game, and the order of their Gen releases. Kanto represents an East, as that's what the tou 東 in Kantou 関東 means.