Ōkuwa (大桑村, Ōkuwa-mura) is a village located in Nagano Prefecture, Japan.The total area of the village is 234.47 square kilometres (90.53 sq mi).The average annual rainfall is 1680 mm with September as the wettest month.[2] Per Japanese census data,[3] the population of Ōkuwa has decreased over the past 60 years.The area of present-day Ōkuwa was part of ancient Shinano Province.