Keywords
Architecture
Castles
Lit. "loophole distribution." The number of loopholes per two meter (one ken 間) interval in a castle. Also refers to the proportion of bow and arrow loopholes to gun loopholes. In the middle ages when firearms bow and arrows were the primary weapon used, the distribution of loopholes was one every 2 m along a castle wall. Five foot soldiers were assigned to each loophole. In the mid Edo period, various schools of military thought had their own formulas. For example, the Yamaga School, Yamaga-ryū 山鹿流 built two musket loopholes to one bow and arrow loophole; other schools had them divided equally.