A castle was planned to be effectively defensive and hard to be invaded by the enemy. Layout of wards (Kuruwa), broadness and depths of moats, figures of earth ramparts and so on are all ingenious attempts. Gate or sally port (Koguchi) of a castle with zigzag path in front of it was one of those contrivances. A zigzag path was formed on both sides or one side of a gate by earthwork so that enemy can't proceed through easily. Types of gates (Koguchi) are illustrated.
Nanbatajō Museum, Fujimi City Municipal Museum of History and Folklore