What is Chōji abura in Japanese Katana terminology?

"丁子油" or "Chōji abura" translates to "Choji Oil" in English. It is a type of plant-based oil used to prevent rust on swords. The oil is extracted from the buds of a tree called "Choji (Clove)". Cloves have been imported and widely used since ancient times, as evidenced by their presence in the Shosoin repository, a famous historical building in Nara, Japan. The oil not only prevents rust but also adds a layer of protection to the sword, preserving its quality and longevity.