In Myeongdong, go to Daiso Myeongdong Main Store (43 Myeongdong-gil) or

Myeongdong Station Store (134-1 Toegye-ro), both open 10am–10pm. The black travel double pouch with carabiner (23×18cm) is ₩2,000 with 6K+ orders. Two pockets keep receipts and your passport apart.