The 1783/1785 Ryukyu Map by Japanese cartographer Hayashi

Nicolas Kristof's blog regarding Diaoyu (Pinnacles Islands aka Senkaku as translated by Japanese) has attracted a letter from the Japanese government. He maintained his view, but also published the letter from Japan to provide the other side of the argument.

This （三国通覧図説 / 林子平 図並説）should be the 1783 map mentioned in Kristof's blog. It was  mentioned by （Japanese version and the source of the map below）Japanese scholar by Kiyoshi Inoue , Professor of History department, Kyoto University

• Ryukyu territroy began from the Kume Island and the area east of it, whereas Chihwei Yu and the Huangwei Yu and Tiaoyu Yu (Diaoyutai) to the west were Chinese territory. Obviously, this was defined in clear terms after the middle of the 16th century at the latest. There are no records or documents whatsoever by the Ryukyu side or the Japanese expressing disagreement or doubt. Moreover, there are not even legends, not to say documents about contacts of the Ryukyu people with the Tiaoyu Island (Diaoyutai) and Huangwei Yu in ancient times. Sailing from Ryukyu to the Tiaoyu Island (Diaoyutai) was particularly difficult because it was against the wind and the tide. In the middle of the 19th century, that is, the closing years of Japan's feudal period, the Ryukyu people knew the Tiaoyu Island (Diaoyutai) as Yokon (or Yokun), the Huangwei Yu as "Kubashima", and the Chihwei Yu as "Kumesekishima". This was confirmed by the records of the last Chinese imperial envoy. These in no way affect the title to these territories. The map and explanations about Ryukyu Kingdom in the book General Illustrations of Three Countries by Shihei Hayashi were completely based on the Chungshan Mission Records. The Chungshan Mission Records had found their way to Japan long ago and there was even a Japanese edition. This document was the most comprehensive and authoritative source of knowledge about Ryukyu for the Japanese people in the late Edo period.

The map labeled the islands in the same color as China's (Qing Empire), most likely because of the recording of shipping route China used to reach Ryukyu.(source: Hokkaido University)

Full Map and Japan Map (日本図 + 三國圖)
三國=琉球、蝦夷、朝鮮，當時皆不屬日本。當時還特別有列明為無主島的，是今天的小笠原群島。(The 3 Country maps means Japan and its 3 neighbors, Ryukyu, Korea and Hokkaido, not part of Japan back then. It also included a section of "uninhabited/un-owned island groups", which are today's Ogasawara Islands)

Ryukyu Map (琉球島図)

Diaoyu and Taiwan portion enlarged (Diaoyu colored same as Qing's, instead of classified as "uninhabited" like Ogasawara. As Professor Inoue indicated, the map is probably created based on his reading of the Chinese travelogue)

Japan was first interested in Ryukyu in 1885 but waited till January of 1895 to formally set claim on the islands, by then the Japanese army had already completely smashed Qing' navy and army, and have taken Lushunkou near today's Dalian in November 1894. The Shimonoseki Treaty was signed in April but the war was almost finished by January. Some used the difference in dates (January vs April) to claim that the Diaoyu was not part of the spoil of the war, but the fact is the Pescadores Islands (Penghu) was taken by the Japanese in March 1895, also before the signing of the Treaty.

However, I am not as confident as Kristof about how ICJ would decide, for reasons outlined by Alexander Peterson.

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The first (full) map above, to the east (actually, between E and ESE) of Ulrungdo (鬱林島）, seems to be an island marked as Korean held (朝鮮ノ持ニ）, seem to fit the relative position of Dokdo (Takeshima) very nicely, and was labelled Takeshima in the enlarged map below.

Enlarged portion shows Takeshima held by Chosen

Below is the Korea map from Hayashi's book, where Ulengdo (鬱林島）is shown as the island very close to the Korean mainland.

Korea Map (朝鮮八道図)

Hokkaido Map (蝦夷国全図)