In this episode, we become familiar with OST mainstays 2NB. 2NB (Korean: ???) is a South Korean R&B duo formed by Friday Entertainment in 2006. The duo consisted of Heo Solji and Kim Song-yi. They released their debut single "The First Fragrance" on March 31, 2006. The group disbanded in 2012. Shortly afterward, Heo Solji became the main singer of the girl group EXID, which debuted that same year. Also, Kim Song-yi became the lead singer of the girl group Blady, which was in 2015. In 2016, 2NB came back with two new members Son Yoo-na and Kim Hyo-jin. [Source: https://en.wikipedia.org/wiki/2NB]