'King of Mask Singer' contestants will be making their guest appearance on MBC's 'Radio Star'.

According to multiple broadcasters, f(x)'s Luna, Kahi, BTOB's Sungjae and composer Kim Hyung Suk participated in the show recording on May 20th.

Many people are looking forward to this episode since they all gained much attention by appearing on 'King of Mask Singer', by erasing people's negative perspective on idols and showcasing their skills as real singers. Composer Kim Hyung Suk was in the judge panel of 'King of Mask Singer', and he's expected to reveal some of the behind the scene stories of the show.

This episode will be broadcasted on May 27th at 11:15PM KST.