Indigo (ai) is a blue die that is extracted from a plant. The die is also known as Japan Blue, and has been providing color to Japanese life since ancient times. There are several facilities in Tokushima where you can learn about indigo dying from experts, and at the Ai-no-Yakata, the refurbished house of an indigo trader that was turned into a museum, you can dye a handkerchief.The way you do this is tying off the parts you do not want to dye with rubber bands, and then dying it in the indigo dye until you get your desired color. This experience takes about 20 minutes, and you can take your finished product home with you.