Ohkuma is located in the centre of Futaba County, 250km north of Tokyo and 103km south of Sendai.
Ohkuma faces the Pacific Ocean in the east and borders Miyakoji Village of Tamura County by the watershed near the Abukuma mountains in the west. It adjoins Tomioka and Kawauchi Village in the south, and Namie and Futaba in the north.
The land is high in the west and low in the east, with the elevation ranging from 695m to 3m above sea level, and covers an area of diameter 15.4km from east to west and 6.7km from north to south.
Of the total area, 65% is occupied by mountains and forests, about 50% of which are state-owned. The Abukuma Mountains stretch out to the ocean to from three undulating hills in the south, centre and north of the town respectively. Among them three rivers named the Kuma river, the Koirino river and the Ottozawa river flow to the east, with cultivated lands in their basins.
The climate here is of an eastern Japan oceanic type and is relatively mild, with the annual precipitation around 1,200mm, and with almost no snowfall even in winter. West and northwestern gusts blow seasonally and sometimes frost and a long spell of rain at the rice harvest time do some damage to the crops. On the whole, however, this region is blessed with mild conditions and is comfortable to live in.
This town was founded as Ohkuma with a population of 8,815, 1,550 households and a total area of 78.50km2, through the consolidation of former Ohno and Kumamachi villages on 1 November 1954 in accordance with the Town and Villages Consolidation Promotion Act.
Ohno village had been founded through the consolidation of three villages (Nogami, Ohgawara and Shimonogami) on 1 April 1889 when the municipality system was put into force, while Kumamachi had been founded through the consolidation of five villages (Kumagawa, Kuma, Ottozawa, Orahama and Koirino).
During the age of the feudal system, this district (including the present Futaba Town) was subject to the manor house of Minami Shineha County, one of seven counties of the Soma Clan. The southern part of the county was bordering on Iwaki. For that reason, it had formed the border protection areas during the age of the Civil Wars. In the age of Tokugawa, a checkpoint was erected at Kuma Post in the year of Genna.
At present, the town is divided into 21 administrative districts. Since the foundation of the town, the population maintained a downward trend for some time as the Japanese economy grew, but it has started increasing gradually since the nuclear power plant was constructed by the Tokyo Electric Power Company Limited in January 1967. As of 30 September 2000, the population is 10,830, the number of households 3,515, and the total area is 78.70km2.