A promotional poster for Busan's "Big Sale Week" event / Courtesy of Busan Metropolitan City

Global cities hosting stadium-sized concerts face a familiar dilemma: Massive crowds arrive, spend money exclusively at the venue and depart, leaving nearby neighborhood merchants with little more than traffic congestion and litter.

Ahead of the upcoming “BTS World Tour 'ARIRANG' in Busan,” municipal officials in the southeastern port city are deploying an aggressive, state-backed economic experiment designed to prevent tourist money from getting left at the concert gates.

The Busan Metropolitan Government announced Monday the launch of “Busan Big Sale Week,” a coordinated economic campaign running from June 10 to 16. The initiative aims to leverage the global star power of the K-pop group to stimulate the city’s retail and hospitality sectors, directly channeling the purchasing power of international fans — collectively known as ARMY — into local small businesses, traditional markets and alleyway commercial districts.

Under the plan, the city has coordinated discount agreements with more than 550 mom-and-pop shops and nine major department stores, including regional branches of Lotte and Shinsegae. To incentivize spending, local authorities are augmenting Busan’s proprietary digital currency, Dongbaekjeon, offering users a 2 percent cash-back bonus at participating stores and launching a 100 million won ($65,314) promotional lottery for consumers who spend over 100,000 won.