Whole red shiso leaves of this quality and size are something special even in Japan. Grown in Kanagawa prefecture they can only be harvested early in the morning before the sun comes out, so that the leaves keep a maximum of moisture. The red leaves are then pickled in salt to preserve them.
Whole red shiso leaves can be used to wrap sushi or rice balls instead of seaweed. The salty savory flavor enhances the aroma of the rice. Red shiso is already an important ingredient for many Japanese pickles to naturally enhance the flavor and add a natural red color.