A castle storehouse surrounded by hills
There are almost always castle ruins at the foot of a hill or at the entrance of a valley. Invaders were attacked from both sides of the valley, and their retreat was blocked. These castles were more like residential houses rather than castles; they are surrounded by clay walls more than 5 meters tall built by piling up earth on all four sides, with a length of 50 meters on each side, instead of stone walls. There are as many as 800 ruins in Iga and Koka altogether.