The Shimane Prefectural Government has confirmed "The New Divisional Map of Whole Japan(改製日本扶桑分里図)"（1768）, which is the original drawing of "Newly-carved Highway Map of Japan(改正 日本輿地路程全図)"(1779) that serve as the basis of Japan’s claim to Takeshima islets in the Sea of Japan.
It shows "Matsushima", today's Takeshima, northwest of the Oki islands. "The New Divisional Map of Whole Japan" is Nagakubo Sekisui's hand-written map and two islands, Takeshima(Ulleungdo) and Matushima(Takeshima) are re-rewritten from north-northwest to the right location with the phrase "“Viewing Koryo is just the same as viewing Inshu (=Oki island) from Unshu (=Izumo) (見高麗猶雲州望隠州)”" which are cited form "Inshu Shicho Gohki". The both islands were clearly depicted as Japanese territorial islands.
First and Second editions of Nagakubo's Kaisei Nihon Yochi Rotei Zenzu left Takeshima and Matsushima uncoloured along with other several islands including Okinoshima, Kuchinoerabushima, Ezo and Hachijojima, likely because they are remote islands.
Nagakubo made the map based on SEKI, Sokoh's "Description on People and Couties ( 新人国記)" (1701) and Mori Kohan's "The Field Chart of Japan, The Atlas of Japan (日本輿地図 日本分野図)"（1754,） both of which showed Takeshima(Ulleungdo) as Japan's. He shifted the direction of two islands apparently based on the phrases from Inshu Shicho Ghoki.
As has already pointed out, Nagakubo had later published historical geography book on China "Map of Asia and Small Orient(亜細亜小東洋圖)"(1835) and it clearly shows Takeshima/Dokdo as Japanese territory. He had compiled the fruits of years of study on geography, astronomy and history into the book. There is no doubt Nagakubo considered both islands as Japanese territory.
Shimane Prefecture also confirmed a rough drafts of "Map of Japan" from the 18th century. (right)
They are the first "whole Japanese map" which plotted Takeshima.
“According to the prefecture, the discoveries include a map draft titled “Kaisei Nihon Fuso Bunrizu” made in 1768 and a rougher draft titled “Nihonzu.”
The maps show islands called Matsushima, the name of Takeshima at the time, northwest of the Oki island chain in what is now part of Shimane Prefecture.
The maps were made by Nagakubo Sekisui, a geographer from Mito in today’s Ibaraki Prefecture. The maps preceded another map called “Kaisei Nihon Yochirotei Zenzu” that was made by Sekisui upon permission from the feudal government of the time that is cited by the current government as the grounds for Japan’s claim to Takeshima.
Nagakubo’s descendants gave the rough drafts to the Takahagi board of education in Ibaraki Prefecture. (Japan Times)”
Shimane Prefecture News Release (Japanese)