Matsunaga is one of the largest manufacturers of sharpening stones in Japan. In the West, these stones are usually known as King stones or Sun Tiger stones. The stones of the King or Sun Tiger series have a relatively soft bond, which allows the abrasives to be continually exposed during use, making the stone highly effective. These stones are particularly suitable for extremely hard, low-alloy carbon steels (White and Blue Paper Steel). Before use, soak the stones in water for at least 15 minutes. They can also be stored in water permanently.