A star-studded viral marketing stunt? This is “How It’s Done.” KPop Demon Hunters stars Rei Ami and Kevin Woo surprised fans with a concert from atop a double-decker bus in New York City on Saturday, August 23.

"KPop Demon Hunters" fans were in for a major surprise Saturday when cast members Rei Ami and Kevin Woo popped up in NYC and led a sing-along to "How It's Done," the intro song to the Netflix hit. The surprise performance was part of a series of "K-Pop Demon Hunters Golden Weekend" events.

The Netflix production KPop Demon Hunters is being showcased in theaters for a limited weekend, featuring sing-along sessions. In a delightful surprise for fans in New York City, the voice actors of the beloved characters took to a double-decker bus to perform several of the songs.