Ota manor covered the greater part of Sera-gun. It was a big manor which
had 613 hectares of cultivated fields in 1190. The retired Emperor Goshirakawa
donated this manor to Koyasan Kongobuji Temple Konpon Daitoryo in Kishu
Province (now Wakayama Prefecture) in 1186. Koyasan dispatched Bana there
as administrator. He ruled for eight years. During the period, Imakoyasan was
built as a key center of the authority of the esoteric Shingon Buddhism.
Koyasan, though far away, made much of this manor and dispatched a monk of
ability as an administrator. Activities of Enshin, who was the administrator in
the middle of the Kamakura period, are well known. However, the influence of
Imakoyasan declined during the end of the period because samurai extended
their powers. From 1573 to 1592, eight branch temples were abolished and only
four, Anrakuin Temple, Kongoji Temple, Fukuchiin Temple and Jodoin
Temple, remained.
 Imakoyasan, which is located at the foot of a mountain in the south of
Kozan-cho(present Sere-cho), has the remains of twelve branch temples built in the Muromachi era. Anrakuin Temple (removed and reconstructed), a two-story
gate to a Buddhist temple, the small torii of Awashima shrine and the main
building of Fukuchiin Temple remain there. At the end of the main approach,
Koya and Mibu Shrines are located, and at the top of the stone steps, the
Kannon-do building and Miei-do building are lined up.