>>46338939No
Very northern island = Sinnoh
Very southern island = Hoenn
Midul of Japan around Tokyo = KANTOOOO, west from there = Johto
Shitty little islands southward = Sevii islands
The "unexplored" regions of Japan are the ones between Hoenn and Johto, north of Johto and KANTOOOO and the highlited spot on OP's map