User blog comment:Dragonjet/KanColle Command Center/@comment-125.54.24.26-20140610225134/@comment-1820055-20140611015345

In layman's terms, DMM website saves your location on its cookie. When restricting users for pages that are JP-only, it just checks the cookie what's your location. If we write on that cookie and say "Japan", it will think you're really from JP and will not restrict you.

On detail, if DMM actually checks if the URL path you are requesting is included in its cookies. So its a URL-whitelist, that when you have a cookie for "/netgame/", you are cleared to go to that directory.