The in Takajà Â-machi, Kà Âchi, Kà Âchi Prefecture, Japan, now permanently closed, formerly housed historical materials related to the Yamauchi clan, rulers of the Tosa Domain. Going back to an agreement between the Yamauchi family and Kà Âchi Prefecture from December 9, 1994, this foundation was formally established as a collaboration between Kà Âchi city and Kà Âchi Prefecture on April 26, 1995, with the aim of preserving and exhibiting the family's ancestral heritage of historical records, arts and crafts items. On May 1 of the same year the museum hall was opened.
The items date to the Edo period and were found in and around KÃ Âchi Castle. Since the Meiji period, they had been in possession of the Yamauchi family. Materials were gradually transferred from the Yamauchi family to the custody of KÃ Âchi Prefecture since April 28, 1995; a process that was completed in July 2004 with the simultaneous transfer of about 36,000 items. Since then, the complete material ancestral heritage of the family, amounting to about 67,000 items, has been held by the archives. In addition the archives have received materials entrusted or donated by temples and shrines.
The museum exhibits the collected items, conducts research and runs training and educational courses. A dedicated department is in charge of restoration and preservation of materials. Regular and special exhibitions on a variety of topics are changed periodically, with about 100 items on display at any given time. The regular exhibition is devoted to the Tosa Domain and the Yamauchi family.
In December 2010, the museum began displaying documents from the Chà Âsokabe clan, which was ruled by Chà Âsokabe Motochika (1539âÂÂ99) from Okà  Castle during the Sengoku period. The documents include the oldest paper known to be signed by Chà Âsokabe Kunichika (Motochika's father), and documents covering the period from when the Chà Âsokabe clan rose to power until just before their decline.
The archives hold one scroll (no. 20) of the Kà Âya edition of the Kokin Wakashà « from the 11th century Heian period. This is the oldest extant manuscript of the work and has been designated as National Treasure of Japan.
The facility permanently closed on 31 March 2016, in preparation for the opening of the KÃ Âchi Castle Museum of History.