Abstract
The Okishio castle site was designated a nationally designated historic site in fiscal Heisei 10 and given the official name of the Akamatsu castle site. Following this, excavations and surveys at the site were carried out by Yumemae-cho Board of Education, Hyogo Prefecture.
The castle was built on Mt. Shiroyama and is known to have been used by the Akamatsu family, the shugo (provincial constables) of Harima. Traditionally the castle is said to have been built in the first year of the Bunmei era (1469) and to have been used by the five generations of the Akamatsu following Akamatsu Masanori.
The ruins of the castle have around 70 enclosures and, with features covering an area of 600m eastwest and 400m north-south, they make up the biggest castle site in Harima. The geomorphology of the mountain castle can be described as forming two summits: enclosure I-1 which had a military function and the residential enclosure II-1 in the western enclosure cluster. In terms of function, these two areas had mutually complementary functions.
During the archaeological excavations, towers were found in the central enclosure and the gate area in enclosure I-I . The presence of these two towers shows that defensive functions were developed and provide proof that this enclosure was the military court (tsume-no-maru).
It was confirmed that many full-scale residential enclosures with gates and foundation stones were constructed within the western enclosure cluster (clusters II-V), particularly in the enclosure II-1 on the mountain summit. Our ex-cavations demonstrated that construction of these residential enclosures was concentrated at the end of the Warring States period during the time from the Eiroku to the early Tensho eras (1557-1581). In other words, it was shown that the date at which the mountain castle was enlarged and became a full-scale residence was 100 years earlier than was traditionally assumed. At the end of the Warring States period, the political power of the Akamatsu is said to have declined during the time of Yoshisuke and Norifusa, but the construction of this castle leads to the opposite conclusion. In this way, the surveys and excavations at the Okishio castle site have brought new perspectives to research on the Akamatsu.
Within each enclosure cluster, the central cluster (such as II-1) was always accessed by corridor 2 . These areas had high-status garden and stone-built facilities. Entrance-shaped landforms were associated with both the western and eastern ends of corridor 2, but they were closed off from the other enclosure clusters making a sort of central space. From this it was surmised that within the western enclosure cluster there was a status difference between the main enclosures centered on II-1 and the lower status enclosure courts. This demonstrates that this area was where the provincial constable displayed his status and ritual authority.
