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
Ri Hak-sung
Kim Dong-hwi
Han Ji-woo
Park Hae-joon
Ahn Gi-chul
Park Byung-eun
Kim Geun-ho
Jo Yoon-seo
Park Bo-ram
Tang Joon-sang
Tae-yeon
Kim Won-hae
Park Pil-joo
Ju Jin-mo
Professor Oh
