Oyoroi (Large Armor) (大鎧)

"Oyoroi" (large armor) is one type of Japanese armor. From the Heian to the Kamakura Period, wars took place where shooting bows while mounted on a horse was the common method of fighting and a superior mounted samurai wore large armor. In the Muromachi Period it was called "Shiki/Shikisho no yoroi" (armor for formal ceremony). In the Edo Period it was called "Honshiki no yoroi" (armor for the main ceremony). Or, it was just simply called "yoroi" (armor) in order to distinguish it from trunk armor (armor put around the torso) and the belly band, etc.

It was influenced by the armor of mounted clans from the Asian continent. The production technique for {Buddhist altar fittings} was used in making armor. Thus during the Heian Period, it established itself as a peculiar Japanese armor with a national cultural style. Concerning the exact time and the process of change from continent's style of armor to Japan's peculiar style of large armor, historical items left behind are scarce and not clear. However, it is generally agreed that the basic style roughly established itself around the mid Heian Period and during the battles on buildings, shooting at each other with bows and arrows. This type of armor were mainly spread among the superior warriors on horses from the Heian to Kamakura Period. Around the period of the Northern and Southern Courts (Japan), when the wars became intensified with group and the close attacks of walking troops, armor around the torso and belly bands became commonly used, and the large armor disappeared from the actual combat. Afterwards, the large armor remained only to show a general's authority and status. In the Edo Period when there was no more war, large armor was symbolically used as a retro armor in the daimyo (feudal lord) family, etc.

Features and structure
During the battles in the Heian Period, one general mounted on horseback leading the troops was the main style. Basically, a general on a horse aimed at his arrows at enemies on his left. Therefore, large armor was important in defending from arrow strikes, and the components, such as the large sleeve (Osode), the chest plates (Kyubi-no-ita), and the sandalwood plates (Sendan-no-ita) were attachments. The fukikaeshi (left and right flips) of the helmet were also large. The armor main body was composed of many pieces of kozane (small plates made of iron and leather), while the trunk was composed of a big flat plate. As seen from a wearer, the front, the left side, and the back are connected as one piece and the missing right side is covered with another piece called the arm shield (waidate). Moreover, a wooden plate (sakaita) is hung on the back and a shoji plate is mounted vertically on the shoulder part of armor. The trunk is not tightened therefore the weight of the armor is mostly on the shoulders. Kusazuri (armor for under body) is attached to protect shield the waist to thighs. Kusasu consists of four flat plates, namely front, back, left and right. The weight is supported by the shoulders when a person is standing while wearing large armor. However, when he is on a horse, the weight of the armor hangs to the saddle and stabilizes the body. The shape also gives priority to defense while the wearer is on horseback. It is armor for battles on horseback and the structure is not suitable for walking troops.

Kozane (small scales made of iron and leather)
The main part of the large armor is composed of strips (made of iron or leather) called kozane. Two rows or three rows of small holes of are made along the kozane and Japanese lacquer is painted on the surface. While these pile up horizontally little by little and connect together, the connected strips are then tied up and joined sideways to form a piece of the armor. With such a structure, the wearer's body can bend and stretch easily. In order to reduce the weight, while small leather scales are used as the main body, vital parts are protected by properly mixing in small iron scales.

The above-mentioned small scales are connected vertically with string and leather in a process called 'odosu (interlacing),' while the resulting piece is called 'odoshi.'
The small scales (kozane) are interlaced together by thick string and leather. According to the color, pattern design, material quality, the string is called "Konito-odoshi (lace with navy blue string)," "Nioi-odoshi (lace with odor)," and "Kozakura Kawa Kigaeshi Odoshi Yoroi (yellow lace with Kozakura leather)." With these, they formed colorful armor of national style.

Leather with dyed pattern
Leather is mounted on the surface of the armor and on the left and right flips of the helmet. It has patterns such as Tasuki-goshi (cross brace), lion or Acala (God of Fire). To prevent the bowstring getting caught to the armor in front of the trunk, a piece of bow leather is put there.

Large sleeve
It is a shield-shaped component suspended from right to left along the armor trunk to shield from the shoulder to the upper part of the arm. It is made with small scales, same as that of the trunk. Usually, it was 6 rows, but it became 7 rows during the Kamakura Period. To stop arrows, it is larger than the sleeves of future generations of armor. The left sleeve is called "Imuke-no-Sode" (sleeve of shooting direction) while the right sleeve is called "Mete-no-sode" (sleeve of horse controlling hand), the left sleeve, which is facing the enemy, is made stronger.

Chest plate, Sandalwood plate
It shields the exposed left chest when shooting an arrow with an open arm. It is attached and suspended in front of the trunk. The right side is the sandalwood plate, while the left side is the chest plate. The sandalwood plate on the right is composed of small scales to ease bending and stretching when pulling a bow, while the he chest plate on the left is often made with one more iron plate because it is close to a vital spot.
Kabuto (helmet)

Hoshi-kabuto helmet and Suji-kabuto (muscle) helmet were used with a large armor. Anyway, attached to the iron-plated hem of the helmet is 'Shikoro' (neck guard). The helmet attached to large armor has 2 big flips of fukikaeshi to protect both sides of the face from arrows.

Kusazuri (armor for the under body)
It is made with five rows of small scales. Since it may be cumbersome on horseback, the bottom part of the kusazuri in the front and in the back are divided into right and left. Also probably because of this, it is not uncommon that the front and back kusazuri were made in 4 rows. The left one is called 'Yunde no Kusazuri' (lower body armor for the shooting arm), 'Tachikake no Kusazuri' (lower body armor for sword-hanging) or 'Imuke no Kusazuri' (lower body armor for shooting), while the right one is called 'Waidate no Kusazuri' (lower body armor for shoulder shield).

National treasures of large armor
Concerning the age of production, there are some slight discrepancies in accordance with the researchers and the literature records. Moreover, for convenience, the kanji characters for "string", '糸' or '絲' are unified as the former simpler one.

The Early Heian Period
Omodaka Odoshi Yoroi (Oyamazumi-jinja Shrine)
The Late Heian Period
Akaito Odoshi Yoroi (odoshi armor with red strings) (Musashi Mitake-jinja Shrine) – handed down from and dedicated by Shigetada HATAKEYAMA
Tatenashi (no shield) (Kanda-tenjinja Shrine) – handed down from the Takeda clan
Konito Odoshi Yoroi (odoshi armor with navy blue string) (Itsukushima-jinja Shrine) – handed down from and dedicated by TAIRA no Shigemori
Kozakura Kawa Kigaeshi Odoshi Yoroi (Itsukushima-jinja Shrine) – handed down from and used by MINAMOTO no Tametomo
Konito Odoshi Yoroi (odoshi armor with navy blue string) (Oyamazumi-jinja Shrine) – handed down from and used by Michinobu KONO
Konito Odoshi Yoroi (odoshi armor with navy blue string) (Oyamazumi-jinja Shrine) – handed down from and dedicated by TAIRA no Shigemori
Akagawa Odoshi Yoroi (red leathered odoshi armor) (Okayama Prefectural Museum)
The Early Kamakura Period
Murasaki Aya Odoshi Yoroi (helmet missing) (Oyamazumi-jinja Shrine)
The Late Kamakura Period
Akaito Odoshi Yoroi (odoshi armor with red strings) (Kiku-kanamono (chrysanthemum ironmongery goods)) (Kushihiki-hachimangu Shrine)
Akaito Odoshi Yoroi (odoshi armor with red strings) (Ume Uguisu Kanamono - plum, bush warbler ironmongery goods) (Kasuga-taisha Shrine)
Akaito Odoshi Yoroi (odoshi armor with red string) (Take Suzume Tora Kanamono - bamboo, sparrow, and tiger ironmongery goods) (Kasuga-taisha Shrine)
Shiraito Odoshi Yoroi (odoshi armor with white string) (Hinomisaki-jinja Shrine)
Asagiaya Odoshi Yoroi (odoshi armor by asagiaya) (Itsukushima-jinja Shrine)
The Period of the Northern and Southern Courts
Shiraito Odoshi Tsumadori Yoroi (Kiku-kanamono) (Kushihiki-hachimangu Shrine) – handed down from and dedicated by Nobumitsu NANBU