2007 and made a debut performance two days later. [ 21 ] That following March, Yesung, Kang-in, Sungmin, Donghae, Ryeowook, and Kyuhyun participated in an original soundtrack for the first time, singing the opening and ending themes "Success" and "H.I.T" for the Korean miniseries, H.I.T . 2007–2008: Setbacks Due to Kyuhyun's severe