Proper care keeps both the steel and the saya in excellent condition over the long term. Every few months, apply a thin coat of choji oil - traditional camellia oil - to the bare blade using a soft cloth, working from base to tip. This prevents oxidation and keeps the hamon visible and crisp. Store the aikuchi horizontally in its saya in a location with stable temperature and low humidity; avoid exterior walls, attic storage, or anywhere prone to humidity swings, which can cause the lacquered wood saya to expand and contract unevenly. Do not leave fingerprints on the blade for extended periods, as skin oils can cause spotting on high-carbon steel. Handled and maintained with this basic routine, a quality aikuchi will remain a pristine display piece for decades.
