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April 1, 1906: Part of Tōbui Village in the former Tōbui District incorporated into Ōtsu Village. Part of Tabikorai Village, Nakagawa District was also incorporated into Ōtsu Village.
April 1, 1955: Ōtsu Village split up among Taiki Town, Hiroo District, Toyokoro Village (now Town), Nakagawa District, and Urahoro.