Kim HeeChul and Irene are colleagues. Kim HeeChul and Eileen are both Korean artists, and they are both artists of SM Entertainment Co., Ltd., so they are colleagues of the same entertainment company. Irene was found in the draft of South Korean SM Entertainment Co., Ltd. in 2009, and Kim HeeChul was selected in the SMStarlightCastingSystem in 2002. The overall musical style of SM tends to dance music, in which rock, jazz, hip-hop and other musical elements are added. At the same time, SM also owns a series of classic songs written by Young Jin Yoo and other composers for SM artists or groups. Although dance music is very popular in the whole Korean music industry, SM's works are unique and unforgettable, which is also beneficial to its excellent music production team. However, SM has always rejected external works, so it has lost a lot of good works, which also makes the overall works have not changed much, and it is inevitable that there is a feeling of deja vu, like works produced on the assembly line (although it is estimated that SM will take this route as long as dance music is still popular).