Natural indigo dye has been used around the world for thousands of years, but the invention of synthetic indigo dye in the 1800s caused the industry to crater. In Japan’s Tokushima Prefecture, only a handful of masters carry on the eight-century-old art of making a unique form of indigo dye called sukumo. But the yearlong process of growing and fermenting natural indigo can’t compete with the efficiency and low cost of synthetic alternatives. Because of this, the denim industry uses about 55,000