The unit is specialized of Bubblegum pop and Novelty-based sound, they officially debuted on June 5, 2008 with their only EP Cooking?
Super Junior-Happy made an unofficial debut performance on May 3, 2008 at the Power Concert although they had not formally introduced themselves as the subgroup at the time.
On the day before their debut, the subgroup held their first sign fan meeting to celebrate the success of the sales of Cooking?
According to the Music Industry Association of Korea, the EP sold 27,122 by the end of August and was ranked fifth in the monthly charts.
[3] Super Junior-Happy performed their second single, "Pajama Party" on August 3, 2008 on SBS's Popular Songs.