It seems to me that Japanese geographers would not include Dokdo on their maps in the 1800’s because no one cared about two worthless rocks in the Sea of Japan at the time. The two rocks only gained value in modern times when national borders and thus exclusive economic zones could be tied to them. Using the logic this Korean researcher is using does he support Japan’s claim to the Kuril Islands based on this map?:
A scholar recently unveiled maps of a government-approved Japanese textbook which show that Japan did not perceive Dokdo as its territory in the 19th century.
The findings will give weight to Korea’s ownership of the islets off the country’s east coast, which Japan claims as its own, referring to them as Takeshima Islands.
Prof. Han Cheol-ho of Dongguk University’s history education department displayed maps of a geography textbook compiled by Okamura Matsutaro in 1886 in a presentation at a conference held at the Northeast Asian History Foundation’s Institute of Dokdo Research last week.
The textbook’s map of Asia does not mark Dokdo as its territory. On the map is a red line marking Japanese territory, but not only is Dokdo not included in the area inside the red line, Dokdo is not marked on the map at all.
The border lines are marked the same way in textbooks compiled by geologist Manziro Yamagami in 1902 and 1903.
“The textbook’s map of Asia has the Oki Islands marked, but not Ulleungdo and Dokdo,” Yonhap News Agency quoted Han as saying.
“If Japan perceived Dokdo as its territory it would have drawn the islets on the map and stretched the line to include Dokdo.” [Korea Times]
You can read more at the link.