Hidden Holes for Shooting
The inside of Tsuru-no-maru Earthen Wall has many hidden holes, through which the defenders could shoot at enemies. From the other side , the side of San-no-maru, it looks like just the plain Namako Kabe wall. Enemies could never see the holes because they are completely hidden by tiles. The defenders break the tiles and use holes to shoot at enemies. Reportedly, Maeda Toshiie was extremely good at using a lance, but since guns were already often used in those days, Kanazawa Castle had various defense systems against guns. Actually, Toshiie built Kanazawa Castle ten years after the Nagashino Battle, in which guns had been used for the first time in Japan.