The "Minami-no-maru", another "kuruwa" shaped like a rectangle, measures about 70 metres (230 ft) from east to west and 110 metres (361 ft) from north to south. The height of the top of the foundation is more than 20 metres (66 ft) above sea level. This "kuruwa" was not only a defence against an enemy approaching from the south but also a kind of "kakushi-guruwa" (hidden "kuruwa") where an ambush could be laid to launch a pincer attack from this "kuruwa" and the "hon-maru" on enemy soldiers approaching the "hon-maru". Some documents indicate that there was a residence for the deputy castellan (the lord's councilor who was in charge of the castle during the lord's absence).