Boom came back as a singer. On August 17, Boom decorated the stage of KBS' "Yoo Hee Yeol's Sketchbook" as a singer.

On the show, Boom explained that he found his own way to sing the song the best and that was lip sync. He added on recommending lip syncing to Yoo Hee Yeol.

Boom showed his own style of high pitched, technical song Kim Tae Woo's "Love Rain" and made the audience laugh by saying, "if you motivate into the song as if you are that singer when you lip sync to the song, your throat will be sore after the performance.'

He also said "if my image before going to the army was cheap style, then after the army is fighting and passion," asking Yoo Hee Yeol to do the opening of his show with more energy.

On the other hand, BoA came out as a guest and gained popularity from the crowd.