O-yoroi

The ō-yoroi (大鎧^?) is a prominent example of early Japanese armor worn by the samurai class of feudal Japan. The term ō-yoroi means "great armor."

Ō-yoroi first started to appear in the 10th century during the middle and late Heian period, and came into widespread use in the Genpei War around the 12th century when the call for armor was at its peak. Significant aspects of this armor were designed for cavalry archers. The box shaped ō-yoroi was heavy and did not allow as much movement or flexibility as its counterpart the dō-maru, so the armor fell out of favor in the fifteenth century when samurai shifted to mostly infantry tactics.

For the most part the ō-yoroi was a rich man's armor and not used by lower ranking samurai. The armor was mainly worn by the higher ranking samurai on horseback. The lower ranking soldiers had armor that was similar to the ō-yoroi, but had fewer components, was lighter, and lacked the decorative markings of the higher ranking samurai.

Most of the information known about the ō-yoroi is based on the armor of the higher-ranking officials since the armor was either donated to a shrine as an offering or maintained by the descendants of the original wearer. Many of the original components of the ō-yoroi still in existence have been replaced over time due to the items being lost or damaged. The few remaining examples of ō-yoroi are on display in museums in several different countries. There are also a few examples of ō-yoroi in Shinto shrines where they have been maintained and protected for centuries.

The basic components of the ō-yoroi and other samurai armor are known collectively as the “hei-no-rokugu” or simply “rokugu,” which means six articles of arms. The six major components are the dō (cuirass), kabuto (helmet), menpo (mask), kote (armoured sleeves), sune-ate (greaves), and the hai-date (cuisses). The ō-yoroi combines plate and scales (kozane) laced together (lamellar). One specific advance over earlier armors is that the kozane of ō-yoroi are first laced together and then covered with lacquer, which enhances resistance to corrosion. The dō of the ō-yoroi is unique from later models because it is composed of two separate parts instead of one piece with an opening on the side or back of the dō to allow the samurai to put on the armor.

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Wikipedia