Kasai Castle, Medieval Japanese castle in Aoto, Tokyo.
Kasai Castle was a medieval fortress in Aoto positioned at a bend in the Nakagawa River and surrounded by water-filled moats. Today the location has become a park where visitors can walk through and see the remaining traces of the former fortifications.
The fortress was built around 1500 and served as an important stronghold for the Uesugi clan during a period of civil conflict. It fell in 1590 when Toyotomi Hideyoshi extended his power over the region.
The park today displays medieval remains and information panels explaining how fortifications were constructed during that era. The layout still reflects how water and natural barriers shaped the way people built defensive structures.
The site is easily reached from two train stations in the area, with Keisei Aoto Station offering the shorter walk to the park. The grounds are open to the public, and spring or autumn are good times to visit for comfortable weather.
After its time as a military stronghold, the grounds were converted into a hunting lodge used by the Tokugawa shoguns. They practiced falconry there, an activity that held special appeal for Japan's ruling class.
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