As it will become pertinent already in 0.1.6.1 coming out on September 15th (some refinements remaining), might as well give you a rundown on how it works.
Initial concept was actually called "passport bro", but region hopping felt more refined. Region hopping unlocks a new region with its own set of girls in their stack, a "staging area" (apartment), but for the first one in the interest of maximizing the continuing of existing progressions, I picked Korea so I could have Yeo-Bin come back alongside Neha and introduce as few new characters as possible (you've already seen the unnamed Korean girl, which will be named by voting).
To unlock region hopping in 0.1.6.1 / 0.1.7 +, you will first have to finish the date with Hong Yeo-Bin (there is talk of visiting Seoul, also I need to send Yeo-Bin to Korea (region 1 as the game understands it).
Future regions (and whether there will be any will be decided by vote). This list is just to fill it up, entirely possible to do Eastern Europe etc.
Previously you just pressed the generic airplane button and you could experience the first part of the Neha / Seoul prologue. This time around, a new tab will be available on your tablet where the regions are listed. The prologue with Neha is only triggered once on the first flight there. You use the same tab to get back to the US.
Neha is going to drop you off to the neighborhood / dong where your apt is, from which you'll be "operating" out of.
I tried to make it as fancy but also styled in the usual "tight quarters" Asia is known for.
Once you're settled in, you'll have access to the new region's stack. Tablet will also only show the map for the region you're in and only the girls present in the region (girls can shift between regions if the story warrants it).
Age and image is still tentative, that's just from a dev shot.
You will have to match with Neha to date her again, after all, you met her at the airport. And from there, you'll see where it goes.