Hong Kong, officially the Hong Kong Special Administrative Region of the People's Republic of China, is a metropolitan area and special administrative region of the People's Republic of China on the eastern Pearl River Delta of the South China Sea. With over 7.5 million residents of various nationalities in a 1,104-square-kilometre (426 sq mi) territory, Hong Kong is one of the most densely populated places in the world.

South Korea, officially the Republic of Korea, is a country in East Asia, constituting the southern part of the Korean Peninsula, and sharing a land border with North Korea. 25 million people, around half of the country's population of more than 51 million people, live in the Seoul Capital Area, the fifth-largest metropolitan area in the world.