SS501's Heo Young Saeng, who's currently on break after promoting his solo album, "Let It Go", will be returning with a new track for SBS's 'Protect the Boss' OST! Heo Young Saeng commented, "I'm extremely glad to be able to participate in the OST for 'Protect the Boss'.�I truly hope that my song will fit in well with such a great drama." His OST track "Sad Song" was produced by composer Jun Hae Sung, who's known for his works with 'Secret Garden' and 'The Greatest Love'. Befitting of its title, the song will be used in sorrowful scenes between the two leads to better express the nature of their love. The song will first be revealed in the seventh episode on August 28th, and will be released officially online on the 31st. Source + Photos: Star Today via Naver