Tokutan Castle was a square enclosure located on a
river terrace on the western bank the
Kitakami River, approximately 356 meters on each side, consisting of an earthen
rampart surmounted by a wooden
palisade.
Yagura watchtowers were erected at 70-80 meter intervals, with gates in the center of each wall facing each of the cardinal directions. The southeastern corner of the castle was a swamp, and it is uncertain of the walls and palisade extended to this area. Also to the east of the castle is a 400 meter long remnant of a canal, which evidently once connected the castle directly to the Kitakami River. Tokutan Castle appeared to have been partially built on top of an earlier site, with dimensions of approximately 150 meters to a side, which was at an angle to, and extended further to the east than the later, larger, enclosure. As with the earlier Shiwa Castle, in the center of the enclosure was a
fortified compound containing buildings for local administration; however, as Tokutan Castle was considerably smaller in scale than Shiwa Castle, it had a garrison of approximately 500 men. Although completed in 811 AD, Tokutan Castle was officially closed only four years later, in 815 AD. After its imperial garrison was withdrawn, the fortifications continued to be manned until sometime in the mid-9th century by the local militia (Emishi who were loyal to the Yamato court), but was eventually abandoned at some unknown time. ==Current situation==