LuLuLun Tokyo Kouji Sheet Masks (7 count)! NWT! Kouji is also the raw material for a cosmetic ingredient called Kojic acid, which has been confirmed to inhibit the production of tyrosine, a cause of aging spots. This limited edition set of LuLuLun sheet masks fight aging, smooth, and moisturize skin. Perfect for achieving radiant skin! I ship within 48hrs!