Hwang Dong-hyuk Director Gong Yoo Kang Inho Actor Jung Yu-mi Seo Yujin Actor Kim Hyun-soo Kim Yeondu Actor Jung In-seo Jin Yuri Actor Baek Seung-hwan Jeon Minsu Actor Jang Gwang Headmaster twin Actor Kim Min-sang Park Bohyeon Actor Lim Hyun-sung Yeonghun Actor Kim Joo-ryeong Yoon Ja-ae Actor Um Hyo-sup Detective. Jang Actor Jeon Gook-hwan Attorney Hwang Actor Kim Jee-Young Inho's mother Actor Park Hye-jin Headmaster's wife Actor Kim Ji-yong Cinematographer Gong Ji-young Writer Mowg Music