Jung II Woo shared, "The scriptwriter Kim Yi Young wrote to Haechi, making a difference from the usual story of King Yeong Jo that was built before. I chose Haechi because the story of this young king appealed to me. "
He said: “While reading the script, writer Kim Yi Young told me a behind-the-scenes story. She told me, "I think you are good at teasing people." There are many such scenes in the movie, so she praised me. I also performed drunk scenes on the first day of filming, and the director said, "I think you are the best if you talk about acting when the character is drunk. I tried to approach and immerse myself in my character".