Bain, a member of the K-pop boy band, Just B, has publicly come out as gay.
The 23-year-old opened up about his sexuality during a concert in Los Angeles.
This is a rare move in a high-pressure Korean music industry, where artists are very guarded about their private lives.
Bain, while performing a solo, said: "I'm proud to be a part of the LGBTQ community - as a gay person."
Videos shared on social media showed the crowd responding with loud cheers.