Busan

is a port city located in the southeastern end of South Korea. The KTX train that Seok-woo took in Seoul was bound toward Busan.

History
When the virus first broke out, the Korean military established a quarantine zone near Busan, and began taking in as much refugees who were displaced in South Korea due to the virus as possible, including Su-an and Seong-kyeong.

However, their efforts of establishing a safe quarantine zone was not successful, due to the fact that everyone was evacuated there, which made it dangerous everywhere. The city eventually fell to a plane with zombies crashing into the city.

Trivia

 * The scene of plane crash in Busan resemble TransAsia Airways Flight 235's crash.