Tokyo's Digital Archive Push Hits a Wall: Duplicate Image Crisis Deepens This Week

Tokyo's drive to digitise its public records, cultural collections and urban planning files has run into a concrete obstacle: thousands of duplicate images clogging government and institutional databases, slowing retrieval systems and inflating storage costs at a time when the metropolitan government is already under budget pressure from yen weakness and rising import costs for hardware.

The problem surfaced visibly this week when the Tokyo Metropolitan Library in Minami-Azabu reported that an internal audit of its digitised photograph collection — covering roughly 340,000 images accumulated since a 2019 digitisation drive — found that an estimated one in six files was a near-identical or outright duplicate. The library, which serves as the metropolitan government's primary repository for historical visual records, launched a manual and automated review process on Monday, July 1, pulling two full-time archivists from regular cataloguing duties.

Why does this matter now? The timing is particularly awkward for City Hall. Governor Koike Yuriko's administration has staked significant political capital on a broader smart-city agenda, and the metropolitan government's Digital Services Bureau is currently preparing a mid-year progress report due later this month. Duplicate image accumulation is not a glamorous problem, but it has downstream consequences — bloated file systems slow the public-facing portals that residents and, increasingly, foreign tourists use to access historical maps, planning documents and ward-level services.

Where the Clutter Is Coming From

The duplication problem is not unique to the library system. The Tokyo Metropolitan Archives in Nishi-Shinjuku, which holds urban planning photographs dating to the postwar reconstruction era, flagged a similar issue in a June 30 internal memo reviewed by The Daily Tokyo. Staff there identified repeated automated ingestion from multiple source departments — particularly from Shibuya Ward and Koto Ward planning offices — as the main driver of redundancy. Each ward uploaded versions of the same site-inspection photographs independently, without a shared deduplication protocol in place at the metropolitan level.

The Digital Services Bureau, established in 2021 as part of the metropolitan government's DX — digital transformation — push, had by April 2026 overseen the migration of approximately 4.2 million files across 23 ward-level systems into a unified cloud storage environment provided under contract with a domestic vendor. That migration, completed ahead of the original June 2026 deadline, was considered a success internally. But the deduplication layer that was supposed to accompany it has not yet been fully deployed, according to procurement documents posted to the metropolitan government's public tender portal on June 18.

Storage costs are a real-world consequence. Commercial cloud storage priced in US dollars has become significantly more expensive in yen terms over the past 18 months, with the yen trading near the ¥158-per-dollar range through much of this spring. A duplicated image library means paying for redundant capacity in a currency environment that punishes inefficiency.

What Institutions Are Doing About It

The Tokyo Metropolitan Library says it has begun trialling a perceptual hashing tool — software that compares images by visual fingerprint rather than file name — across a pilot batch of 20,000 photographs this week. If the trial, running through July 18, meets accuracy benchmarks, the tool will be applied to the full collection by September.

The Edo-Tokyo Museum in Ryogoku, currently undergoing a long renovation, has kept its digitised collection on a separate system specifically to avoid entanglement with the metropolitan database consolidation. That decision, made in 2022, now looks prescient — the museum's digital team told The Daily Tokyo it had no duplicate accumulation issues as of this week, having run a deduplication check quarterly since 2023.

For residents and researchers who rely on these systems, the practical advice from archivists is straightforward: if a public search portal returns unexpected errors or slow load times over the next several weeks, the review process is likely the cause. The metropolitan government has said normal retrieval performance should be restored across most systems before the end of July. Ward offices in Chiyoda and Bunkyo have already issued brief advisories on their websites warning of intermittent slowdowns in document retrieval services.