The Yomiuri Shimbun

Workers put the finishing touches on a batch of kaku kanten, a specialty of the Suwa region of Nagano Prefecture that utilizes the bitter winter cold in the production process. Kaku kanten is a form of agar, a vegetarian substitute for gelatin produced by boiling tengusa and other plants. Employees of Marugo Shoten, a major manufacturer and seller of kaku kanten, come out early in the morning and lay out fresh agar in blocks about 30 centimeters long and 4 centimeters wide to expose them to the cold wind. The finished kaku kanten emerges from a two-week cycle of freezing in the morning, thawing in the daytime to expel moisture, then freezing again at night.