By May 09, 2021 2015 is often considered one of the best years of the third generation of K-pop, with numerous outstanding K-pop groups making their debut that year. Want to know which K-pop group that debuted in 2015 are best-sellers on Gaon? Then keep on reading! SEVENTEEN is the Best-Selling K-Pop Group That Debuted in 2015 on Gaon According to data from Gaon Music Chart, SEVENTEEN is the best-selling K-pop group among idol groups that debuted in 2015, with 6,539,468 online and offline album sales. SEVENTEEN has seen success on the Gaon Charts very early on in their career. (Photo : SEVENTEEN Twitter) Their second mini-album, "Boys Be," which was released on Sept. 10, 2015, scored a nomination at the Gaon Chart K-Pop Awards. In 2020, their seventh mini-album "Heng:garae" sold 1,00,000 copies in under a week, making the group official million sellers.