In public, he adopts a "happy, energetic" face and is shown to be often smiling, even when making eye-contact with strangers in social surroundings. These traits, however, mask his true psychopathic, violent and sadistic characteristics. Sangwoo is actually a cruel and ruthless individual who kidnaps, abuses, tortures, assaults and kill people, showing absolutely no mercy to his victims. He tortures his victims slowly, yet with a certain pace, selecting to also manipulatively coddle them.