SM Entertainment told Korean media outlet TV Report, “After directly asking Super Junior’s Sungmin, he’s said that they’re in the midst of a good relationship.
By 2008, all of the Super Junior members have already been a member of at least one subgroup except Kibum. Super Junior-Happy performed their second single, "Pajama Party" on August 3, 2008 on SBS's Popular Songs. "Pajama Party" promotions only lasted a month, and promotions for the EP officially ended on September 7, 2008.
Super Junior-Happy consists of every previous member from Super Junior-T except Heechul, who is replaced by Yesung.
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 May 30, 2008, SM Entertainment released the official announcement of the subgroup through Newsen.
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.
Super Junior-Happy debuted on June 7, 2008, performing their first single, "Cooking? Close to 10,000 copies were sold by the first week of release.
On the day before their debut, the subgroup held their first sign fan meeting to celebrate the success of the sales of Cooking? On the morning of June 6, over thousands of fans lined up for tickets to the fan meet, overcrowding the streets.
SM Entertainment has confirmed earlier speculation that Super Junior’s Sungmin is dating Kim Sa Eun.
Super Junior’s Sungmin and actress Kim Sa Eun are reportedly dating.
According to a report on September 24 by Woman Chosun, Sungmin and Kim Sa Eun, who met last year through the musical “The Three Musketeers,” were previously spotted on a date watching the musical “Priscilla” on July 17.
One witness said, “Sungmin had a hat pulled on low so as not to be seen, but the two looked close like boyfriend and girlfriend.” Prior to this report, there were also rumors going around on various social networking sites about the stars’ relationship, netizens having seen similarities in the stars’ outfits and accessories in photos they had posted online.