Trainees in the Korean idol industry. But not just any trainees: ones who poured their trainee lives into hip-hop form and turned their debut album into a record of their experiences. From the beginning, BTS’s music reflected the lives of the members. The B-side tracks in 2 COOL 4 SKOOL, “Intro,” “Interlude,” “Outro,” and “Skit,” became a template on which later albums would be formatted. It was a time when only the tiniest minority knew of the Bulletproof Boy Scouts. But BTS were already forging their own identity, one they hold on to today.