The
Shoku Nihongi records that in 741, as the country recovered from a
major smallpox epidemic,
Emperor Shōmu ordered that a monastery and nunnery be established in every
province. These temples had the dual purpose of promoting Buddhism as the
national religion of Japan and standardising control of the
imperial rule to the provinces. The actual date the Hitachi Kokubun-ji was founded is unknown. Per the "Hitachi-Fuchū Kagami", the temple was founded in 743 and consecrated in 752. The original design of the temple was a walled square compound measuring 270 meters east-to-west by 240 meters north-to-south. The compound contained a large
South Gate, Middle Gate,
Kondō, Lecture Hall,
Cloisters,
Rectory and a seven-story
Pagoda,
sutra library,
Bellfry,
Kuri, and monk's dormitory. However, as the buildings of the modern temple partially overlap the foundations of the ancient temple, the exact size and placement of many of the structures of the ancient temple are uncertain. The site was surveyed in 1977 and
excavated in 1982 at which time it was estimated that the original Kondō was four times larger than the present temple's Hondō.The patterns on some of the roof tiles are identical to the eaves tiles found at the
Heijō-kyō palace site in
Nara, suggesting that experts from the central government were providing technical guidance when the temple was constructed. Per the
Engishiki records of 927 AD, the temple was one of the richest in the
kokubunji system in terms of rice revenue. The temple was destroyed once by a fire, some 80 years after it was founded, and again in 939 during the rebellion of
Taira no Masakado. It was rebuilt both times, but was against largely destroyed by fire during the battles of the
Satake clan in the
Sengoku period, the last of which was in 1585. The temple went into rapid decline afterwards, and by the
Keichō era (1596–1615) it did not even have a resident priest, but was reduced in status to that of a subsidiary chapel of a neighboring temple called the Senjū-in. In 1919, Senjū-in and Kokubun-ji merged to form the current Kokubun-ji, and Senjū-in was abandoned. The temple's Sanmon is the only surviving structure of Senjū-in, and is designated a Tangible Cultural Property of Ishioka city. File:Hitachi-kokubunji yakushi-dou.JPG|Yakushi-dō File:Hitachi-kokubunji-ato kondou.JPG|Site of the original Kondō File:Hitachi-kokubunji daishidou.JPG|Kōbō Daishi-dō File:Hitachi-kokubunji sanmon.JPG|former Senjū-in Sanmon ==Hitachi Kokubun-niji==