In "Mask" it turned out that Yoo In Young was the culprit that had killed Soo Ae.
On the SBS Wednesday/Thursday drama "Mask" broadcast on July 2nd, Mi Yeon (played by Yoo In Young) was shown to be present. Mi Yeon had her birthday party with Ji Sook (played by Soo Ae) and went into the room pretending that she was tired after partying. Suk Hoon (played by Yeon Jung Hoon) came home after sending away customers. He thought that Mi Yeon was asleep and went out to where Eun Ha (played by Soo Ae)'s bones were in the moratorium.
Mi Yeon followed Suk Hoon and thought back to past events after finding out that Eun Ha had died. Eun Ha was in a party at the swimming pool when she drank a poisoned wine. With that, she started to falter back and forth. The person that had arranged for this was Mi Yeon. Mi Yeon started to hold Eun Ha so that she wouldn't sleep. At the same time, he was unable to catch on and it turned out that Eun Ha fell into the pool and drowned.
At that moment, Min Woo (played by Jo Ji Hoon) was drinking wine at the same place. He too lost his consciousness and tried to conduct emergency procedures. Nonetheless, Eun Ha ended up dying. This had all been crafted by Mi Yeon who cleared it up on the CCTV to make sure she wasn't found to be the murderer.
