Lee Jai-jin, born on July 13, 1979 in Busan, is a South Korean singer, dancer, and former member of the boy group Sechs Kies. He first entered the entertainment industry after being discovered in his hometown Busan, where he and Kim Jae-duck formed the dance crew "Quicksilver." He was recommended by Lee Ho-yeon to Daesung Entertainment and officially debuted with Sechs Kies in 1997. The group, which Lee provided choreography for, was immensely successful but disbanded in 2000. Lee pursued a solo career, releasing albums like S.Wing in 2001, 002 J2 in 2003, and It's New 2005, though they did not match his group's earlier success. After completing his military service, Lee stepped away from the spotlight to study in Japan, returning to participate in various projects, including illustration work for Big Bang in 2011 and opening a restaurant in 2013. In 2016, he reunited with Sechs Kies for a comeback on the show Infinite Challenge, signing a contract with YG Entertainment for both group and solo activities. He briefly joined the variety show Flower Crew in 2016 but left to focus on his music career.