This gusuku castle is located inside of Iso Koen Park and is said to have been the residence of King Eiso. The rough stone walls are covered in trees and there is an old cobbled stairway. The site has become a sacred precinct in the Aza-Iso area. Visitors can experience the true atmosphere of an ancient Okinawan castle here. In Iso Koen Park an old Omoro ballad praising King Eiso is inscribed in stone on a monument.