In the first round, the singer introduced herself with the mask 'Harley Quinn' and sang with 'La La Land'. The two worked together to give their cover of S#ARP's "Sweety". Despite the song being fairly old, the idol and 'La La Land' worked together extremely well.

'Harley Quinn', however, lost in the first round and had to unmask herself. Many were surprised to see April's maknae and lead vocal Jinsol, singing Im Se Jun's "Don't Go Today". Not too long after revealing her identity, the entire studio quickly fell in love with her strong, emotional vocals. 

Were you surprised to see Jinsol on 'Mask King'?

1. Jinsol
2. mask king