Yuuki Mayu Kougei, most prominent in Ibaraki Prefecture, is a silk thread is made from silkworm cocoons, with raw silk used for dyed kimonos and silk floss for tsumugi fabrics. A key step in preparing silk floss is boiling the cocoons in baking soda to soften them and remove sericin, a natural gelatinous substance. Though the process has a distinct odor, it’s essential for crafting Yuuki Tsumugi fabric. Each cocoon is cut open, dyed, and sewn by hand, and can be turned into nostalgic, textured items like hats—made from natural materials and even washable.