Carbon-steel odachi require consistent, simple maintenance to remain in pristine display condition. The most important step is periodic application of a light coat of choji oil (or a modern equivalent like camellia oil) to all bare metal surfaces — blade, habaki, and any exposed fittings. In dry climates, every two to three months is typically sufficient; in humid coastal environments, monthly attention is more appropriate. Before oiling, remove the previous coat using a soft cloth or traditional uchiko powder ball to avoid buildup that can trap moisture. Store the sword horizontally on a stand with the edge facing upward, which is the traditional Japanese orientation and distributes the blade's weight evenly along the saya. Avoid displaying odachi near heating vents, windows with direct sunlight, or areas with fluctuating humidity — temperature cycling is a primary cause of lacquer crazing on the saya and slow oxidation on unprotected steel. Never store the blade inserted in the saya for extended periods without inspection, as trapped moisture between blade and scabbard is the most common cause of surface rust on display swords.
