Ōi River
In 1906, a joint venture company, the was established, and began studies and design work on plans to exploit the potential of the Ōi River and Fuji River in Shizuoka Prefecture. The British interests were bought out by 1921, and the company was renamed , for its plan to divert water from the Ōi River to the Hayakawa River in Yamanashi Prefecture through a system of penstocks, and thus generate electricity. Work on the Tashiro Dam began in 1924 and was completed in 1928.