The Inoimon Gate is one of the most important gates located on the west side of the castle and plays a key role in the defensive structure of Himeji Castle. The gate was designed to make it difficult to attack in a straight line, and its position in relation to adjacent walls and buildings was devised so that the defenders could fight to their advantage before the enemy could reach the gate. In addition, the strong construction of the gate itself and its exquisite harmony with the stone walls enhance its defensive function.