In Seongsu, go to Daiso Seongsu 2-ga Store (106 Seongdeokjeong-gil) or Ttukseom

Station Store (6 Achasan-ro), both open 10am–10pm. EDIYA Beanist Special Edition (12 sticks) is ₩2,000 with 4.2K+ orders; each stick is 1g, light to carry to work. Seongsu is packed with cafés, so have Daiso coffee at the hotel in the morning and save the café lines for the afternoon.