An earth-paved bridge or wooden bridge was built over the moat at the koguchi that faced enemies, the plates of the wooden bridge were removed or broken to separate the inside from the outside of the castle or the inside from the outside the citadel, or a special bridge designed to be mobile was moved.
敵と対面する虎口の堀には土橋や木橋が架けられ、必要に応じて城内と城外、城内と郭外を遮断すべく木橋の板をはずす、もしくは、破壊、特殊な場合はあらかじめ可動式にして移動した。