The Shibahara family were the largest landowners and salt merchants of the Nishihama Salt Farm. They worked as managers of Ako Domain’s warehouses, and they also served as village leaders in Shioyamura. These historical documents, which belonged to the Shibahara family and were stored at Shinko-ji Temple, include things such as the Nenjuyojihikae (“Year-round Business Memoranda”), a collection of memoranda that was continuously added to over an approximately 120-year period from Kan’en 1 (1748) to Keio 1 (1865). In addition to showing us what Ako Domain and Shioyamura were like at the time, this collection of precious historical documents gives us a window into the management of salt farms during that period and allows us to understand things such as trends in salt-shipping boats and the development of salt farms. In Heisei 18 (2006), the collection was designated as a Tangible Cultural Property (Historical Documents) of Ako City. Currently, the documents are being reprinted and published in a series called “History of Ako City: Historical Documents Collection.”