Happiness! Hello, I'm Seulgi! Seulgi (Korean name: Kang Seul-gi; Hangul: 강슬기) is a South Korean singer. Seulgi began training at SM Entertainment in 2007. On December 2, 2013 she was one of the first three trainees introduced to the public through SM Entertainment's pre-debut project, SM Rookies. On August 1, 2014 Seulgi made her debut as a member of Red Velvet.