BTS fans take photos of the group's pop-up store, BTS POP-UP: MONOCHROME, in Seongdong District, Seoul, April 26. Yonhap

Seoul's Seongdong District has been abuzz in recent days as crowds, many donning purple, gather near a studio building.

The reason for the excitement? Fans of the worldwide superstar BTS — or ARMY — have convened from across the globe to visit the group's latest pop-up store, BTS POP-UP: MONOCHROME.

Despite the absence of K-pop group members currently fulfilling mandatory military services, excitement at the venue remained palpable. More than a week passed since the store's opening on April 26, but eager fans still endured staggering wait times on Saturday afternoon, some even waiting up to more than eight hours.

One ARMY said that she waited for five hours just to secure entry.

"This is my second visit. The first time, I arrived at 2 p.m. and entered at 7 p.m. Today, I arrived at 10 a.m., and we entered around 2 p.m. It's quite a wait, but definitely worth it," Ines, a 25-year-old Portuguese student studying abroad in Korea, said.

Alongside Ines, a diverse array of visitors, including fans of all ages, leaving with bags full of merch, contributed to the vibrant atmosphere around the store.

BTS fans line up to enter the group's pop-up store, BTS POP-UP: MONOCHROME, in Seongdong District, Seoul, April 26. Yonhap

The concept behind this pop-up is to deliver memories of BTS to fans worldwide through "memory clouds," dubbed "monochrome."

The "memory cloud" concept, symbolizing every moment shared between BTS and ARMY stored in a metaphorical cloud, debuted at the group's 2018 fan meet-and-greet event.

Upon entry, visitors are provided with a luggage tag at the check-in desk, entering a space designed to replicate a logistics warehouse. Stacks of wooden boxes and parcels surrounding conveyor belts create a warehouse ambiance.

Inside, visitors encounter memories associated with BTS while viewing previously unreleased black-and-white photos of the members and music videos. Additionally, they have the opportunity to obtain a special certificate to commemorate their visit from a booth located at the exit.

BTS fans take a look around the group's pop-up store, BTS POP-UP: MONOCHROME, in Seongdong District, Seoul, April 26. Yonhap

Aashni, a 20-year-old British BTS fan who first discovered the group through the 2019 hit "Boy With Luv," praised the pop-up.

"Back in my country, it's not as open and friendly about fan culture, whereas here, I can meet people in the same situation, all here to support BTS. The overall experience has been so positive" she said.

She particularly appreciated how the pop-up facilitated socialization among the dedicated ARMY.

"If you are an introvert like I am, you might have to force yourself to try it, but I managed to chat with many different people and the conversation just carries on. It's really nice."

The pop-up event runs through May 12, and is set to travel to Japan, Indonesia, Thailand, the United States, the Philippines and other countries thereafter.