In Keicho 20 (1615), the mound was planted with pine trees that acted as "shitomi-uemono" (visual barriers), prevented landslides, and served as windbreaks, as flaming torches, as building materials, and as emergency food. On the western and eastern sides, the mound lines have many "ori" (cremaillere, a front or face with receding steps, which consists of short and long branches) which permit flanking fire. The "byobu-ori" (tenaille lines formed by making alternate angles salient and re-entering), which can be seen from the south of the inner castle to the area to the east of the inner castle, is enormous. In general, "byobu-ori" have been shown to resemble the defensive lines of western fortifications. They thus bear eloquent witness to the depth of the foresight of "Kuroda Yoshitaka".