The idea for Masquerade developed from the true story of missing records totalling 15 days from the Annals of the Joseon Dynasty. Knowing that the king was kind, but paranoid, the staff constructed this idea as something that could have happened during that undocumented time.
Woo-Suk Kang was originally set to direct, but due to trouble in production's development, Kang dropped out of project and Chang-min Choo on board to helm this film instead.