As previously reported, the sole male member of Sunny Hill, Jang Hyun, will be beginning his mandatory military service. To fill up the empty spot, A-list idols will be temporarily joining Sunny Hill for the promotions of their latest track, "The Grasshopper Song".

On January 27, Loen Entertainment revealed, “Following the performance on “M! Countdown” where Monday Kiz’ Hanbyul joined the group for a special stage, Heo Kyung Hwan, MBLAQ's Thunder and IU will be standing on stage with Sunny Hill on KBS “Music Bank”, MBC “Music Core” and SBS “Inkigayo”, respectively.”

“We're disappointed with Jang Hyun's enlistment, but we're also gaining a lot of strength from the people that have come to help us out. We will work hard to show better performances and better attitudes,” Sunny Hill said.