With a little more than a month left until BTS’ historic return to the stage, Seoul is already feeling the heat. The group’s concert on March 21 at Gwanghwamun Square — their first full-member performance in over three years — has sent ripple effects through Seoul’s hospitality, retail and aviation industries, with nearby luxury hotels booked out and even budget motels hiking rates to nearly 500,000 won ($344) a night. Hotel industry data and tourism platforms show that the “BTS effect” is alrea