As all Korainians learn in Geography of Uji, The Mainland is divided into three principal regions — Lower, Mid, and Upper — which are further organised into eight sub-regions. The principal Upper Region is comprised of the City Korai and  Upper Region sub-regions. As a result, 'The Upper Region' is commonly used  for both the wider region, including City Korai, and for the sub-region below the city itself.

The Upper Region sub-region occupies the hilly, cliff-lined landscape between City Korai and the rest of The Mainland. Its steep terrain, winding routes and individually designed homes distinguish it from the more uniform residential grids of the Mid and Lower regions. Many of its homes are privately commissioned, giving the area a varied and distinctive architectural character.

The sub-region also contains several established commercial and production districts. Atelier Yard houses Calcite Textiles, Dadi Garments and a cluster of smaller clothing makers, while the Commerce Zone  provides allotments for specialist artisans, including jam-makers and master furniture craftsmen. Essential facilities such as Ozai Ink Incorporated are also based in the sub-region.

Together, these institutions position The Upper Region as the pinnacle of commercial production — bridging The Mainland's Mid and Lower regions with the finery of City Korai.