Researchers have discovered more than 1,000 new historical records, including letters and opinion papers addressed to Tomomi Iwakura (1825-1883), a statesman who played a key role in the 1868 Meiji Restoration, by Meiji Era leaders Takamori Saigo, Toshimichi Okubo and Hirobumi Ito.
It is rare for such a large trove of historical documents to be found, especially given that researchers believed they had unearthed almost every document related to the Meiji government, which saw Japan's transformation into a modern industrial state from a feudal polity.
The historians say the records — kept privately by an art gallery in Hiroshima Prefecture — could underline the assumption that Iwakura, who in 1871 became "udaijin" (minister of the right), the No. 2 post after "dajo daijin" (the grand master of state), obtained various types of information from across Japan for policy formulation.
The material could also provide fresh perspectives on the study of the final phase of the Edo Period (1600-1868) and the Meiji Era (1868-1912), they said.
Jun Misawa of Kumamoto University, Joji Fujii of Kyoto University and Suguru Sasaki of Nara University are leading a group of historians studying the records, which the Hiroshima gallery obtained about 20 years ago.
The historians, who embarked on a three-year study last year, estimate that about 80 percent of some 1,700 documents held by the gallery have never before been examined.
The historians said Iwakura is believed to have received the materials in Tokyo from 1868 to 1883, when he died.
They found 68 letters by Ito, 429 letters by Sanetomi Sanjo, who was dajo daijin, Iwakura's superior at the time, and 128 draft letters by Iwakura.
The originals of 191 letters by Okubo, whose existence was already known, were also found.
The historians plan to publish their findings in 2011 after studying all the documents.