Kang Dong-hyeon (Oh-soo's dad, hotel magnate and politician) Kang Heui-soo (Oh-soo's elder brother) Choi Na-heui (Heui-soo's wife) Na Seok-jin (Heui-soo's secretary, one of Oh-Soo's high school gang) Yoon Dae-shik (DEAD - loan shark and one of Oh-Soo's high school gang) Kim Soon-ki (Paroled homicide, one of Oh-Soo's high school gang) Kim Yeong-cheol (Classmate and victim of Oh-Soo's gang, now working as a copy editor) Ban Chang-ho (Oh-soo's boss) Lee Min-Jae (detective) Shin Jae-Min (detective)