North Korea effectively has a one-party system. In theory, there are two other auxiliary parties, but in real life, they exist only on paper. So for every North Korean, the word party unconditionally means the Workers’ Party of Korea (WPK).

According to WPK statutes, every citizen of the DPRK above the age of 18 can apply for party membership. From the official North Korean point of view, all South Koreans are citizens of the DPRK — the Republic of Korea does not legally exist in North Korean laws — meaning they are technically eligible to join the North’s ruling party as well.