Yang Kun
On 4 January 2019 (episode airing on 11 January 2019), the seventh season of China's long-running singing competition "Singer" (which was also called "I Am a Singer" before 2017) began taping, and Kostov was revealed as the last of the seven first-round performers competing this season, which cast also consist of veteran Chinese singers Liu Huan, Chyi Yu, Yang Kun, Wu Tsing-fong (of the band Sodagreen), Zhang Xin, and Escape Plan; all seven singers carries an exemption of participating in the Breakouts and will automatically qualify for the finals if they survived elimination for the entire 11 weeks of performances. At age 18 at the time of the taping, Kostov was also the youngest contestant in "Singer" 's history, and the first ever contestant born in the 21 century. Kostov was eliminated from the competition on week six (2nd Challenge Round), but was however eligible to participate in the Breakout round (due to be held after the 4th Knockout Round, on March 29), to reinstate him from the competition and compete in the finals.