It is made of bricks and the outer and inner walls are similar to the Military housings, but the interior is divided into a front and a back room.
In the front room, Yodansei (a kind of well) was built to lift up the cannon balls to the upper battery.
At the left side of the entrance, there is also a narrow traffic route (lighting room) for managing the lighting in the Ammunition chamber.
There was also a crane neck shaped equipment called “Tsurukubi-youdanki” which was equipped outside the Ammunition chamber for lifting up the cannon balls from outside.