The helmet bowl is constructed of fifty-two ridged plates and is shaped like a melon (akodanari), with a pronounced rise at the back. It dates from the fifteenth century but was remounted for use in the late seventeenth or early eighteenth century. The bowl is inscribed with the character Kami (or Tatematsuru), used by the Haruta school of armorers in Nara. The badge on the turnbacks of the neck guard is that of the Sanada family, daimyo of Ueda.

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