National Treasures & Important Cultural Properties
of National Institutes for Cultural Heritage, Japan

It says "Daishu (collections of poetry)" at the beginning. It contains explanations about chokusenshu (collections of poetry compiled at Imperial request) from Manyoshu to Kokinshu to Kinyoshu and lists private collections and the names of selectors. This copy seemed to have been created approximately in the mid Kamakura period. It is valuable material since it lists the names of anthologies and authors that have been scattered or lost. It is supposed that the copy was made soon after the original was written. 　
Chokusenshu means a collection of poetry compiled at the order of an emperor or a retired emperor. There are a total of 21 chokusenshu from Kokin Wakashu (905) to Shinshoku Kokin Wakashu (1439) and that are collectively called "21 daishu." Some divide them by the time when they were compiled and call them "Sandaishu (Kokinshu, Gosen Wakashu, Shuishu)" or "Hachidaishu (Kokinshu, Gosenshu, Shuishu, Goshuishu, Kinyoshu, Shikashu, Senzaishu, and Shin Kokinshu)."