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.

Top Cast

Choi Min-sikRi Hak-sung

Kim Dong-hwiHan Ji-woo

Park Hae-joonAhn Gi-chul

Park Byung-eunKim Geun-ho

Jo Yoon-seoPark Bo-ram

Tang Joon-sangTae-yeon

Kim Won-haePark Pil-joo

Ju Jin-moProfessor Oh