Oshu-do

…Depending on the position of the hinge, the gold do is classified as a two-plate do with one hinge on the left side or a five-plate do with two hinges on each side. The iron plates are also vertically or horizontally joined or made of a single piece of iron, and the nail heads are enlarged and fitted with washers, or the nail heads are not exposed and are fastened by a mechanism, each of which is a technique that takes practicality into consideration. Of these, the two-plate do with horizontal joints is called Okedo, and the five-plate do with vertical joints or a single piece of iron was popular with samurai from the Kanto and Tohoku regions and was called Yukinoshita-do or Oshu-do. Many of the two-plate do with a single piece of iron have lacquer work applied to the center of the do, or are embossed with decorations, and the famous Tenjin-do made by Kato Yoshiaki is named after the Tenjin with lacquer work on the front. …

*Some of the terminology that refers to "Oshu Do" is listed below.

Source | Heibonsha World Encyclopedia 2nd Edition | Information

…金胴は蝶番の位置によって，左脇1ヵ所の二枚胴と左右2ヵ所ずつの五枚胴の別があり，さらに鉄板も縦矧や横矧，または一枚鉄とし，釘着の鋲頭も大きくして座金（ざがね）を入れたり，鋲頭を出さずにからくり留めとしたりして，それぞれ実用を考慮して技巧をこらしている。このうち横矧の二枚胴を桶胴（おけどう）といい，縦矧または一枚鉄の五枚胴は関東から東北の武士に喜ばれて雪ノ下胴とか奥州胴といわれた。一枚鉄の二枚胴は，胴の中央に蒔絵をほどこしたり，装飾を打ち出したものが多く，加藤嘉明の所用として著名な天人胴は，正面の蒔絵の天人による名称である。…

※「奥州胴」について言及している用語解説の一部を掲載しています。

出典｜株式会社平凡社世界大百科事典 第２版について | 情報