In Myeongdong, go to Olive Young Myeongdong Town (53 Myeongdong-gil, 1F–2F) or Central Myeongdong Town in M Plaza (27 Myeongdong 8-gil, B1–3F), both open till 10:30 PM. Sensitive skin? Look for ZEROID Soothing Cream (10K+ reviews), often with a bonus mini. Creams over 100ml go in checked luggage; use the minis on the plane.