Noh decided to cast Yoo within five minutes of meeting him, saying, "I can't forget the first five minutes I met Yoo at the audition. When I asked other actors about Jong-dae character, they usually answered, 'I think he's going to wear something, have some hairstyle and some kind of personality'. But he stared out the window for a long time, and suddenly said one word as if he choked up slightly, 'It's sad.' At that moment, I thought, 'Jong-dae is him.'" During the film's press junket, Noh said, "In contrast to his noticeably good looks, he was filled with a furious energy. When I hear the word 'youth,' I think of Yoo Ah-in. The true main character of this movie, I think, is [not Jong-dae but] Yoo Ah-in."