president of the Dormitory Student Council who frequently sleep walks. Ahn Dong-goo as Choi Byung-tae, a military academy cadet who likes Hye-ryeong. Kim Jong-soo as Kim Man-dong, a facility manager at Hosu Women's University. He is later revealed to be a North Korean spy. Kim Jeong-hoon as Kim Sang-beom, Man-dong's son, who has a gambling addiction. Nam Mi-jung as Oh Deok-shim, a chef at Hosu Women's University. People around Gang-mu and Han-na Lee Hwa-ryong as Ahn Gyeong-hui, the Chief of the Anti-Communist Investigation Bureau (ANSP), who is later promoted to the Chief of the Office of Planning and Coordination (ANSP). Baek Ji-won as Choi Mi-hye, a fashion designer and Ahn Gyeong-hui's wife. Jang Tae-min as Choi Hui-jun, Eun Chang-su's secretary. Moon Yoo-kang as Seung-jun, a member of the ANSP team. Choi Kyung-hoon as Oh Dong-jae, a member of the ANSP team. Choi Yoon-je as a member of the ANSP team. Others Park Ye-ni as Kim Ye-ni, a secretary at ‘Charmant’. Kwon Han-sol as Han-na Lee Joo-ahn as Jun-pyo, the son of the President of South Korea. Kang Moon-kyung as Park Moo-yeol, a presidential candidate and member of Aemin Party. Cameos Lee Jung-hyun as Park Geum-cheol, a North Korean agent and Soo-ho's colleague, who committed suicide upon his arrest by Gang-mu. (Eps. 1 - 2, 12) Song Geon-hee as Eun Yeong-u, Yeong-ro's brother, was forcibly sent into the military by his father after his involvement in the democratic protests was discovered. During a military operation he switched places with a fellow soldier and was killed during the engagement at the West Sea. (Eps. 2, 5 - 6, 8) Chae Won-bin as Lim Soo-hui, Soo-ho's younger sister. (Ep. 10) Yum Jung-ah as Song Hye-joo, the former housemother of Hosu Women's University dormitory. She was believed to have committed suicide but it was later revealed that Man-dong had killed her as she had found out his secret identity as a North Korean spy. Episodes Production Development Written by Yoo Hyun-mi and directed by Jo Hyun-tak, Snowdrop is their second collaboration after having worked together on the hit satirical thriller Sky Castle (2018–19). Based on the memoirs of a man who escaped a political prison camp in North Korea, Yoo Hyun-mi had been planning the series for twelve years. The early working title of the series was Leehwa Women's University Dormitory (). Casting On June 18, 2020, media reported that Kim Hye-yoon, who was