Kyuden Isawa

Kyuden Isawa is easily the most important publicaly known holding of the Isawa (the most important secret holding being Gisei Toshi).

The Isawa Library
The most important feature of Kyuden Isawa is its library, which occupies nearly the entire castle. The Isawa library dwarfs all others throughout Rokugan in sheer volume, its monumental amount of available information completely unrivaled within the empire. The library is kept by dedicated Isawa librarians and scribes. (Phoenix p. 30)