Hong Kong doesn’t have a capital.
Hong Kong isn’t a country, it’s official full name is Hong Kong Special Administrative Region. The latter part (SAR) is there because HK is still a part of China, but doesn’t follow the same laws as mainland China. At the very least, Hong Kong is a city, hence unable to have a capital city in its area.
The main government building and the Legislative Council building is located in Central, Hong Kong Island. So you could count that as the center of Hong Kong’s political structure, but certainly not a capital.
