Area: ca. 730㎡
Elevation: ca. 37m
Length (extension) ca. 28m
Height (extension) ca. 5m
Ido (well)・ Idomaru-yakata (house for well)
Idomaru-yagura (turret)・Idomaru-mon (gate)・Dobei(earthen walls)
Although only a narrow Kuruwa (defensive territory), it played a central role in the protection of Uwajima castle's water supply and was equipped with a strong stonewall, turret and gate at its entrance. Shikibu-maru also has a well, but this well is larger, with a diameter of 2.4m and a depth of 11m. By utilising the valley’s topography, a natural water channel provides fresh water through this well.
（Drawing of Uwajima Castle (detail) 1699）