Here for your review and comments is a Japanese German Style Civil Helmet described by Paolo Marzetti as used by the civil defense in the 1920' and 30's.
Picture from the publication "Imperial Japanese Army and Navy Uniforms & Equipment" by Tadao Nakata and Thomas B. Nelson":
Picture from the publication "Imperial Japanese Army and Navy Uniforms & Equipment" by Tadao Nakata and Thomas B. Nelson":
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