The Kofuku-ji Temple, located in Nobori Ooji-cho, Nara City, Nara Prefecture, is a head temple of  the Hosso-shu Buddhism sect and it was a private temple of the Fujiwara Clan. The principal image of the Buddha is Shakanyorai. The temple is  9th in sequence of the 33-temple  Kannon pilgrimage and 4th of the 49-temple Yakushi Pilgrimage in Western Japan.
Koufuku-ji Temple was originally built in 669 by the wife of Fujiwara Kamatari under the name of Yamanashi-dera in Yamashina-ku, Kyoto City. It was transferred by Fujiwarano Fuhito to its present location and renamed  Koufuku-ji.
Ooyu-ya is a medieval style bathhouse standing in the east of the Gojyuuno-to, or Five-story Pagoda. It is not known in which year the bathhouse was built, however, the current building was reportedly restored in 1426. It is now designated as a national important cultural property.  
The bathhouse is 7 meters wide north to south  and 7 meters wide east to west with a Hongawara tile roof. The west side of the bathhouse has the Irimoya roof style and the east side has the Kirimoya roof style.  Inside the bathhouse are two gigantic iron pots  that are  used to make steam for a steam bath.
After the Middle Ages, the bathhouse was also used as a meeting place for public uprisings.
  The bathhouse is tremendously valuable as an example of bathhouse architecture from the Middle Ages.