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Two images side by side, the left showing before treatment of a document with Japanese letters on it and red ink borders showing tearing and creasing. The right image shows after treatment condition, with the tears and the creases gone.
Tokujō gun gokuhi, 1945. Left: before treatment. Right: after treatment. Shuhan Suzuki, 2024.

Top Secret! Conserving Japanese Military Documents from World War II

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The following is a guest post by Shuhan Suzuki, a conservator from Taiwan, specializing in paper and Asian painting. She moved to the United States in 2015, where she focused on Asian painting and paper conservation at a private studio in Washington, D.C. She is a Library Technician in the General Collections Conservation Section for the Library of Congress. Her work includes treatments for general collection items, such as books and paper, as well as conservation projects involving rare books.

In March 2024, a researcher visited the Asian Division Reading Room to look at three Japanese military documents. The Asian Division determined that the condition of these documents would not allow for safe handling by the researcher and requested that I perform conservation treatment to facilitate safe access.

These documents are titled “Soren chōhō no tokuisei ni tsuite” (On the peculiarity of Soviet espionage), and “Soren no shihō seido ni tsuita : tsuketari, Hafu Kangoku no genjō” (The judicial system of Soviet Union, with addendum on current prison conditions in Khabarovsk), and were produced in 1941, while the third, “Tokujō gun gokuhi” (Military intelligence secrets) is from 1945.

Three documents side by side, the left showing the front cover of the Japanese military document with both red and black ink and in good condition, the middle image showing the back of the document with some broken fragments lying next to it, and right image showing a different document of a finer white paper showing creasing and tearing.
Three Japanese military documents before conservation treatment. Left: “Soren chōhō no tokuisei ni tsuite,” 1941. Middle: “Soren no shihō seido ni tsuita: tsuketari, Hafu Kangoku no genjō,” 1941. Right: “Tokujō gun gokuhi,” 1945. Library of Congress Asian Division. Shuhan Suzuki, 2024.

These three Japanese military documents are Asian Division collection items. Following World War II, nearly 300,000 volumes were added to the collections. The documents they contain were initially requisitioned by the Allied forces in Japan and sent to the Washington Document Center (WDC) between 1945 and 1952. Both of “Soren chōhō no tokuisei ni tsuite” and “Soren no shihō seido ni tsuita : tsuketari, Hafu Kangoku no genjō” were catalogued to note the individual WDC number on the front cover.

These military documents were designated gokuhi (top secret). Both “Soren chōhō no tokuisei ni tsuite” and “Soren no shihō seido ni tsuita : tsuketari, Hafu Kangoku no genjō” have red 極秘 (top secret) stamped on the top right cover. In contrast, “Tokujō gun gokuhi” has each page bordered in red with 特情軍極密 (Military intelligence secret) at the top and a caution advising to burn the document upon reading and to use with extreme caution.

Three images side by side depicting close up shots, the left showing red pencil with letters and numbers, the middle showing a Japanese stamp in red coloring, the right image showing a series of Japanese letters.
Left: a handwritten WDC number on “Soren chōhō no tokuisei ni tsuite”. Middle: a red stamp indicating gokuhi (top secret) from “Soren no shihō seido ni tsuite: Tsuketari, Hafu Kangoku no genjō”. Right: the page heading on “Tokujō gun gokuhi” with related warnings about its use. Shuhan Suzuki, 2024.

As I worked on these three documents, I gained an understanding of their content. Both “Soren chōhō no tokuisei ni tsuite” and “Soren no shihō seido ni tsuita : Tsuketari, Hafu Kangoku no genjō” were published by the Military Intelligence Department of the Imperial Japanese Army’s Manchuria Special Unit 3036 in 1941, the same year the Soviet-Japanese Neutrality Pact was signed. These publications were primarily circulated among high-ranking military generals to provide them with the latest intelligence reports.

Three images side by side with close up detail of the Harbin prison statement. The left image is a close up shot of a diagram of a cigarette, the middle is a close up of Japanese letters, the third shows the outline of buildings on a plan from a bird's eye view.
Left: example of concealment in a cigarette. Middle: table of street communication gist. Right: detailed diagram of Harbin prison statement. Shuhan Suzuki, 2024.

Both of “Soren chōhō no tokuisei ni tsuite” and “Soren no shihō seido ni tsuita : tsuketari, Hafu Kangoku no genjō” are single folded folios bound with staples at the side. “Tokujō gun gokuhi” is printed on typewriter paper and stapled at the top left. The pages are brittle and prone to breaking due to the acid and lignin in the wood pulp used to make the paper. The folded pages cannot be opened freely as they tend to break along the fold lines.

Given the time sensitivity, the conservation focused on non-aqueous treatments to stabilize the pages. This included removing rusted staples and cotton cords for disbinding, removing degraded cellophane tapes from the cover, flattening cockled pages with tacking irons, filling large losses of paper with heat-set tissues, and mending tears and splits with thin Japanese heat-set tissues.

After treatment was completed, the foldout was carefully refolded into its original format. The pages were then labeled in their original order and housed in custom polyester film enclosures, allowing researchers to move and inspect the fragile pages without causing further loss. The polyester-sleeved pages were stored in a four-flap enclosure in a portfolio binding.

Three images side by side, with the left showing a before treatment image of the Harbin prison document, the middle showing during treatment, and the right showing after treatment.
Results of treatment on “Soren no shihō seido ni tsuita : tsuketari, Hafu Kangoku no genjō”. Left: before treatment. Middle: after treatment. Right: after treatment with page folded back to its original position. Shuhan Suzuki, 2024.
Two images side by side, the left showing before treatment of a document with Japanese letters on it and red ink borders showing tearing and creasing. The right image shows after treatment condition, with the tears and the creases gone.
Results of treatment on “Tokujō gun gokuhi”. Left: before treatment. Right: after treatment. Shuhan Suzuki, 2024.
Two images side by side, with the left showing the repaired Japanese document placed inside mylar sleeves and labelled. The right shows the same document placed inside an archival board 4-flap enclosure.
Left: individual polyester film enclosures in original order labeled on the top right. Right: housed in a four-flap enclosure in portfolio binding. Shuhan Suzuki, 2024.

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