Ji-woo, an outcast at a prestigious private school, meets Hak-sung, the school janitor who is actually a mathematical genius who defected from North Korea.
Choi Min-sik
Kim Dong-hwi
Park Hae-jun
Park Byung-eun
Jo Yoon-seo
Tang Joon-sang
Kim Won-hae
Ju Jin-mo
Kim Hee-jung
Kang Mal-geum
Joo Ye-rin
Jung Seung-kil
Shin Jae-hwi
Kang Joon-kyu
Kim So-suk
Choi Jae-sup
Ro Jong-hyun