An arrow loophole in a castle wall. Also sengan 箭眼. Characterized by a vertical opening about 45 cm high (1 shaku 尺, 5 sun 寸) and about 12 cm wide (4 sun 寸). While its necessary for the opening to be wide enough to see the target, if it is too wide, enemy forces might use it to enter into the castle. The bottom of the opening is about knee high, enabling arrows to be shot at a steep downward angle; a castle was usually raised above the enemy position. The arrow holes were hourglass-shaped *uchisoto hachimonji 内外八文字, narrowing at the center with wide openings on either side. This gave the widest possible shooting range and flexibility from the inside, and the minimum exposure to the enemy. Yazama were classified into seated or standing loopholes *isama 居狭間 and *tachisama 立狭間, respectively.