Nori used for sushi, was called Asakusa nori for the following reasons: 1. The Sushi started in Edo (now Tokyo). The nori was caught in Tokyo Bay, therefore named for the downtown area of Tokyo. The town of Asakusa, then center of entertainment, was a brand name of nori. 2. Asakusa nori is a different nori you can eat now, softer, sweeter, and tastier than the current nori (called Susabi-nori). Asakusa nori listed in the Red Book and it is danger of becoming excinct. We cannot catch them in Tokyo Bay anymore, only southern sea of Japan . Also, nori used to dried under the sun and roasted on a charcoal fire. This process is no longer used.