Japanese Stamps Digital Museum

新大正毛紙切手(輪転版) << 1926年(大正15年) ~ 1937年(昭和12年) >> みほん 1-4-3

Tazawa new kegami stamps 1 Issued on 1926(taisyo15) - 1937(syowa12) - Specimen -

New Taisho kegami / Showa White Paper Stamps 1 - Specimen -
Issued on 1926(taisyo15) - 1937(syowa12)
The Great Kanto Earthquake struck in 1923. Subsequent adjustments to the printing equipment corrected the printing surface dimensions. As a result, the new Taisho kegami stamp was issued from May 1926.Also, in 1937, the anti-counterfeiting technology evolved with the adoption of a new printing machine, so it was changed to white paper.

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The above is only true for specimen stamps.
For more information and official printed stamps, see this.
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