Yosukata pans have already been pre-seasoned but still need to be seasoned. Our pans were treated at a high temperature at production, leaving the color naturally uneven. Despite this initial pre-seasoning, it still needs to be fully seasoned with vegetable oil or lard.
If you buy a pan that has not been pre-seasoned, you will need to heat it to a very high temperature without oil until the color changes to blue. Only after pre-seasoning can you season it with oil. If you wash a fully seasoned pan with dish soap, the patina will be destroyed, and the pan should be seasoned again.