Original Nakai Collection consists of about 2,500 materials passed down through the Nakai family, the Tokugawa Government's master carpenter family in Kyoto, including the plans of Nijo Castle, Kyoto Imperial Palace, Shimogamo Shrine and other shrines and temples, concerning documents and maps. The original collection is now divided into the holdings of several institutions such as Kyoto University Library, Imperial Household Archives, Library and Archives of Kyoto Institute and the Osaka Museum of Housing and Living. The materials held by the Osaka Museum of Housing and Living are well acknowledged for their value in the architectural history research and designated as important cultural properties.
- AY2016 68 maps dizitized and published
- AY2017 249 plans and related documents of Nijo Castle digitized and publicized (Feb. 27, 2018); 1 map publicized.
- AY2018 4 illustrated plans regarding the accessions of the emperors digitized and publicized funded by Kyoto University Rare Materials Digital Archive Fund (Mar. 29, 2019).
- AY2019 1,067 items related to the Kyoto Imperial Palace (Feb. 21, 2020) and 13 items related to the Tokugawa Government (January 27, 2020) digitized and publicized.