academic value for Japan are listed in a three-tier system. Properties in need of preservation and use are catalogued as "Registered Cultural Properties". Important objects are designated as "Important Cultural Properties." Important cultural properties that show truly exceptional workmanship, a particularly high value for world cultural history, or an exceptional value to scholarship can be designated as "National Treasures." In order to achieve the designation, the owner of an important cultural property contacts or is contacted by the Agency for Cultural Affairs for information regarding the registration. In the latter case, the agency always asks the owner for consent beforehand, even though not required by law. The agency then contacts the Council for Cultural Affairs, which consists of five members appointed by the minister of education for their "wide and eminent views on and knowledge of culture." The council may seek support from an investigative commission and eventually prepares a report to the Agency for Cultural Affairs. If they support the nomination, the property is placed on the registration list of cultural properties, the owner is informed of the outcome, and an announcement is made in the official gazette. The designation policy is deliberately restrained, keeping the number of designated properties low. In this respect the South Korean protective system is similar to that of Japan. In the 21st century, up to nine properties were designated every year. Categories The Agency for Cultural Affairs designates tangible cultural properties as National Treasures in thirteen categories based on type. The agency generally distinguishes between and . Each main category is divided into subcategories. The 230 structural cultural properties are separated into eight categories, and the 906 fine arts and crafts cultural properties are separated into seven categories. Castles The category includes nine designated National Treasures located at five sites (Himeji Castle, Matsumoto Castle, Inuyama Castle, Hikone Castle, and Matsue Castle) and comprises eighteen structures such as donjons, watch towers, and connecting galleries. Himeji Castle, the most visited castle in Japan and a World Heritage Site, has five National Treasures; the other castles each have one. The designated structures represent the apogee of Japanese castle construction, and date from the end of the Sengoku period, from the late 16th to the first half of the 17th century. Built of wood and plaster on a stone foundation, the castles were military fortifications as well as political, cultural, and economic centers. They also served as