There are several artists with the pseudonym NK:
These are photos from concerts where NK played, so they may be of other bands that played the concert as well.
Fall Out Boy / NK May 26, 2013 Boston, Massachusetts, United States Uploaded by Krista
Fall Out Boy / NK May 25, 2013 Montréal, Québec, Canada Uploaded by Vanessa Hébert
Fall Out Boy / NK May 21, 2013 Pittsburgh, Pennsylvania, United States Uploaded by Gabrielle C