What is Yoroidoshi Tanto

"Yoroidōshi" (Samurai Armour Piercer) is a type of short katana, a tantō, which was used as an auxiliary weapon during the era when samurai fought while wearing armor (kabuto and yoroi). Although not many exist today, they are very popular as concealed weapons (anki) for assassination in fictional works such as anime, manga and games, so many people know the term. This article will introduce the basics of yoroidōshi, we will introduce some famous examples, and hopefully it will give you inspiration for your own custom tanto.

Features and Uses of Yoroidōshi

A "Yoroidōshi" (Armour Piercer), also known as "Metezashi" (Horse-Hand Stabber), is a type of short sword used in close combat with an opponent wearing armor. Samurai armor is strong and cannot be cut with a katana, but it has a weakness. That is the gap at the joints. Yoroidōshi were made for the purpose of stabbing this weak point. Because it is held in the reverse grip, the blade length is less than 9 sun 5 bu (about 28.8 cm), the length up to the elbow. Also, when attacking a castle, its robustness was utilized to insert it between the stone walls and use it as a foothold. It's said that when the yoroidōshi was worn at the waist, unlike a regular sword, the handle (tsuka) was positioned at the back, and the end of the scabbard (kojiri) at the front, to prevent the blade from slipping out naturally during a grapple or being stolen by the opponent. This can be seen in paintings depicting Sengoku-era warlord Hosokawa Sumimoto.

Yoroidōshi Mountings
The mountings (koshirae) of existing yoroidōshi are mostly aiguchi koshirae (mountings without a handguard (tsuba)), similar to a typical tantō. Because it was meant to be drawn only with the right hand from the right hip, the parts such as the kurigata (part of the scabbard through which the cord, sageo, is passed) and the kaerizuno (fixture for catching on the belt when drawing the sword from the scabbard) are on the outside, or what would be the "uragawa" (back) on a normal sword, with the head of the kaerizuno pointing toward the kojiri. The reason for the head of the kaerizuno being affixed in the reverse direction is a device to prevent the scabbard from being drawn out when the yoroidōshi is drawn with the right hand alone. The cord was entangled with the kaerizuno or passed through a hole called "Inu-mekake" made in the kojiri to prevent the scabbard from slipping off.
Famous Yoroidōshi Tantō Inscription: Yoshimitsu (Famous Atsushitōshirō)
The "Tantō Inscription: Yoshimitsu" is a short sword listed in the Kyōhō Meibutsucho, known by the nickname "Atsushitōshirō". This sword, made by swordsmith "Tōshirō Yoshimitsu", is a typical yoroidōshi with an exceptionally thick layer. Initially owned by the Ashikaga shogunate, it passed through the hands of various people including Toyotomi Hideyoshi's retainer "Hitotsuyanagi Naosue", and Sengoku warlord "Kuroda Takatō (Kuroda Kanbei)" before finally reaching the Tokugawa shogunate. It is currently held by the Tokyo National Museum in Taito Ward, Tokyo.
Famous Yoroidōshi Yoroidōshi Inscription: Chōunsai Tsunatoshi, Date August of Tenpō 7
The "Yoroidōshi Inscription: Chōunsai Tsunatoshi, Date August of Tenpō 7" is a yoroidōshi produced by "Chōunsai Tsunatoshi", a swordsmith active during the Edo period. This sword features a deep curve and a "Kissaki Moroha-zukuri" style, where only the point/kissaki part is double-edged. The maker, Chōunsai Tsunatoshi, was a disciple of "Suishinshi Masahide", known as the "father of the Shinshintō era", and a highly skilled swordsmith. He is also known as the "foremost person of the Bizen tradition" in his time and is said to have established a major school in Edo during the Bakumatsu period.