Ōi, Kanagawa  Ōi is located in hilly west-central Kanagawa Prefecture, bordering on the Tanzawa Mountains. During the Edo period, the area around present-day Ōi was part of Odawara Domain in Sagami Province. After the Meiji Restoration, it became part of Ashigarakami District in Kanagawa Prefecture. On April 1, 1889, the district of Ashigarakami was administratively divided into villages, including Kaminaka, Soga, Yamada and Kaneda. On November 3, 1943, the villages of Yamada and Kaminaka merged to form the village of Aiwa. Aiwa later lost a portion of its territory to neighboring Nishihadano on June 20, 1956. The remaining portion merged with Kaneda and portions of Soga to form Ōi on April 1, 1956. The economy of the Ōi is primarily agricultural.