Japanese chefs always use a wet and a dry towel next to their cutting board in order to wipe their knife between cuts. First, they use the wet and then the dry towel. This practice is very important especially when you are using a highly reactive steel knife.After you have finished your meal preparation, thoroughly clean your knife with mild hot water, mild detergent and a soft sponge. Never use strong detergents, wire sponges or the hard side of the sponge. Immediately after washing it, carefully wipe your knife with a soft water absorbent towel. Be extra careful to dry some tricky parts like the handle/blade transition area.
Most of the handmade Japanese knives (with the exception of the stainless steel ones), are highly reactive and prone to rust. After cleaning and drying and before storing them, is suggested to use a mineral oil on the blade to prevent corrosion. The appropriate oils are mineral food grade oils like Camelia seed oil. Using a cloth, you just apply a thin layer of that oil on your blade. If rust appears, use a rust eraser(link) – a rubber compound bonded with medium or fine grit abrasive that is used in carbon steel knives to remove easily rust. Can be used with water or with water and baking soda combination .
Cleaning the Whestones and Nagura
An important step that is usually forgotten is the cleaning of the sharpening wetstones. Put them under running water (not hot) and rub them either by your hand, a soft plastic brush or your nagura stone until all marks and steel particles gone. Put the stones in your dish rack to dry and store them only after they are completely dry. Never expose your stones to direct sunlight to dry. Rinse with water the rest of your equipment, dry and store them.