The owner of the 'ghost mask' was Sim Hyeong-tak.
On the latest episode of the SBS "My Sassy Girl - Drama", Gyeon-woo (Joo Won) was locked up in prison and wasn't on very good terms with Princess Hyemyeong (Oh Yeon-seo).
Jeong Gi-joon (Jung Woong-in) was thinking of a plan when an arrow flew into his room. It was no other than the 'ghost mask'.
'Ghost mask' had always been silent for the last 10 years but on this day, he charged at Jeong Gi-joon saying, "You're done for". However, he was caught by Jeong Gi-joon's men. The person behind the mask was Choon-poong (Sim Hyeong-tak).