A staple of K-pop concerts is the meticulously rehearsed choreography and CD-quality vocals prepared for every performance of the night. For their New York City debut, BTS did that, of course, but also showed a more relaxed and freer side of themselves that made the show that much more memorable -- even with an abrupt finish.

Introducing themselves to the sold-out Best Buy Theater crowd in matching military jackets, the septet opened with "N.O" that showcased their polished, hip-hop-inspired choreography from the get-go with B-boy moves, slinging hats around their body and, at one point, member Jimin flipping over his band mates. But as the guys moved into third song of their Red Bullet setlist, "We On," they moved away from the in-sync moves and instead freestyled throughout the whole performance -- which is rather rare for K-pop acts and even more rare that they can look natural doing it.

It was during these less-calculated performances that BTS was able to show how comfortable they are onstage and with one another. For example, when one member rapped, the others would chime in on different phrases for that extra oomph. The BTS boys riffed off each other's energy, touching and interacting with one another the whole night. During standouts like "Look Here" and "Miss Right," BTS had the potential to get sloppy and boring, but instead it felt casual and fun like the fans were really watching the boys just do what they love.

Not to say the stylized performances didn't impress either. "Blanket Kick" was adorable as the guys sang around a bed, hugging one another and made cute faces for the audience. The performance of their debut track "No More Dream" once again brought out their B-boy style and acrobatic moves, like running on each other's backs, while "Tomorrow" was a powerful reminder of why BTS' dance skills are a sight to see in K-pop.

Despite how much love the packed crowd was giving BTS -- with the NY crowd cheering particularly loud anytime Suga had a solo -- the guys' set came to an abrupt close one song into their encore due to alleged threats to the members surfacing on social media during the show. While the band wasn't able to perform their latest single "Dope," if anything, the curtailed, impressive showing could just make fans that much more amped for the next concert that's likely to be even bigger for the quickly rising boy band.