The Department of Ancient Materials is engaged in the study of historical materials concerning the Nara, Heian, and Kamakura periods (from the 9th to the 14th century). The Department of Medieval Materials is engaged in the study of historical materials concerning the Muromachi and Azuchi-Momoyama periods (from the 14th to the 17th century). The Department of Early Modern Materials is engaged in the study of historical materials concerning the Edo (Yedo) period (from the 17th to the 19th century). The Department of Old Documents and Diaries is devoted to the study of, obviously, old documents and diaries. Finally, the Department of Special Materials is devoted to the study of various special materials including cultural properties, Japanese old-style signatures, historical geography, and overseas materials relating to Japan.