K-pop supergroup BTS reunited with fans after a four-year hiatus following completing mandatory military service. The free comeback concert in Seoul drew tens of thousands of fans, with thousands of police closing streets and roads. The band's leader, RM, told the crowd: "Annyeonghaseyo!" as they opened with "Body to Body." The performance launches a global tour, which analysts predict could generate hundreds of millions of dollars in revenue per quarter. The event followed the release of BTS' fifth album, "ARIRANG," which sold nearly 4 million copies in its first day. BTS debuted in 2013 and has a global supporters, including members of the “Army” and the first K-pop act to top Billboard’s Hot 100 chart in 2020.