 The Yodo River is noted for having the largest number of tributaries of any river in Japan, and for supplying water for the Hanshin Industrial Region.Ōtsu was historically noted for the production of several products, including Ōtsu-e, a form of folk drawing purchased by travelers in the Edo period; the Ōtsu soroban, an abacus used widely in Japan from the early 17th century; Zeze-yaki and konan-yaki, forms of ceramics produced in the Edo period; and Zeze-cha, the first Japanese tea to be exported to the United States.Ōtsu, while not an agricultural city, is home to the production of edible chrysanthemums, used in Japanese cuisine in tempura and decoratively on platters of sashimi.