Nakadera Haiji Historical Site is the site of a forest (mountain) temple from the Heian Period (794-1185) built in the Sanuki Mountain Range, which forms the border between Kagawa and Tokushima prefectures. A forest temple is a temple that served as a base for monks and nuns on their ascetic practices in the forest. The temple consisted of three buildings on a slope at an altitude between 600 and 700 meters. Excavations have found traces of pagodas, Buddha halls, and other structures.
　Temples built between the Asuka (538-710) and Nara (710-794) Periods were generally built on flat ground, but when mountain Buddhism began spreading during the Heian Period (794-1185), large forest (or mountain) temples such as Enryakuji Temple on Mt. Hiei and Kongobuji Temple on Mt. Koya started being built.
　Nakadera Haiji was designated as a historical site in 2008 because it is an important indication of the spread of Buddhism and forest temples into local areas during the Heian Period.
　The site is now a historical park where the cornerstones of the pagoda and Buddhist hall have been restored, enabling visitors to see the position and size of the structures.
　There is also an observatory that overlooks the Manno-ike Reservoir (famous for being built by Kobo Daishi (Kukai) during the Heian Period), the Seto Inland Sea, and the major plains of Kagawa Prefecture, including Takamatsu and Mitoyo Plains.