Dashi Windows
Hishi Yagura and Gojukken Nagaya have bay windows, whose structure is called "dashi." With the "dashi" structure, the floor next to the window would open with the system called "ishi-otoshi," or stone dropping. By opening up the floor next to the window, you can see the moats and stonewalls very easily. If your enemies are invading, you can drop stones on them using this slot.