The Kurosaki Battery ruins in Iki City are a sight to behold, with the ability to launch massive shells weighing approximately one ton, with a caliber of about 41cm and a barrel length of about 18m. As a fortress with remnants of war, it is a tourist spot with high historical value. The interior is pitch black and the viewing area is limited, but you can imagine what it was like at the time. It's a must-see for those interested in Japan's castle construction or war history enthusiasts!