Murasame-jo Castle and Jizen-jo Castle, built during the Warring States period, belonged to the Koka warriors.
The castles are surrounded by high embankments, where the structure of the entrance pathway to Jizen-jo Castle in particular, consists of complicated curves to obstruct the enemy's direct approach into the castle. The two castles were built side by side and are thought to have functioned as one.
An ultimate lord did not emerge during the Warring States period in the Koka region. Lords of each region cooperated to govern the area, calling the self-governing unit, “Koka Gunchuso”. As each lord in the region built their own castle, the ruins of many castles can still be seen in Koka City today.
Many castles with complicated structures were built especially in the Shinji and Sugitani areas of Konan Town in Koka City. This is thought to be because the Rokkaku clan, which was chased by Oda Nobunaga in 1568, temporarily hid out in this area and used it as their military base.