In the past, former members of IOI appeared on the variety show and proved themselves as amazing vocalists! On this week's episode, another member from the disbanded project group sang on the show, behind the mask of 'Yong-Shim'. Going against her opponent 'Harney' in the 1st round, 'Yong-Shim' and the female singer sang "Password 486" by Younha. 

Although both singers were applauded for their unique vocal abilities, 'Yong-Shim' unfortunately lost against 'Harney', unable to move up to the next round. Before she left the stage, she delivered her solo stage with the song "I'm OK" by Taeyeon. 

Then, when 'Yong-Shim' unmasked herself, the crowd went wild as they saw Kim Do Yeon standing on the stage! Formerly known as the IOI member, Kim Do Yeon now introduced herself as the current member of Weki Meki. 

Were you able to guess Kim Do Yeon's voice from the 1st round? Watch all the clips above!