The tachi (太刀 or older 大刀) is a sword possessing a curved blade of about 70 cm, precursor of the classical Japanese sword. It is mainly a cavalry weapon.
The term "tachi" probably comes from the verb "tachikiru" (断ち切る) meaning "to cut in half". It first appears in the Tōdai-ji kenmotsuchō (register of objects owned by the emperor).
The combination of kanji can be translated as:
The tachi differs from the katana in several characteristics:
From a purely metallurgical point of view, old tachi cannot compete in quality with later blades.
This is due to the fact that Japanese swords are made of tamahagane, a less pure satetsu (iron sand) with a lower carbon content than Eurasian and modern steel.
Only a few blades from this period remain, and most of them have been stored in relatively poor conditions, so they are in a condition that does not allow us to appreciate them properly.
However, these blades remain of considerable historical importance and are exhibited in many museums for this purpose.
Tachi are generally divided into two groups by the Japanese, kazaritachi (lit. "decorative tachi") and jintachi (lit. "war tachi").
Etymologically, the term tachi/tachikiru is close to mapputatsu, it means "to open in two", "to slice something".
In reality, kazaritachi are, a bit like in the West, ceremonial swords, mainly used at the imperial court by the kuge and more rarely by the high ranking buke when visiting the imperial palace in Kyoto.
The term refers first of all to the frame, often extremely refined, with gold and pearls, the samehada covering the wood of the tsuka is usually not covered with silk, and the tsuba is typically a luxurious kara-tsuba (Japanese interpretation of a Chinese sword guard).
The blade itself has nothing to do with it. Although some kazari-tachi were unsharpened or unremarkable, just as court swords in Europe had ceased to be functional.
Jintachi, on the other hand, had a more sober and practical mount, oriented for the battlefield.
They are closer to the katana, and are favored by samurai horsemen, and therefore, often worn by high ranking samurai until the Sengoku period (the daisho is standardized at the very beginning of the Edo period). It is therefore the type of sword that daimyos and samurai generals tend to carry.
In other words, jindachi are aesthetically based on a formal, sober and functional beauty, while kazaridachi aim at showing the noble rank, thus its dignity, and the power of its bearer.
There is a serious misinterpretation of the word "jintachi" in the West, and one can find on the web blades with a strange, serpentine curvature of the handle. This is pure fantasy. Jintachi are very normal tachi.
In general, the curvature of a tachi is of the "koshizori" type (accentuated curvature on the first third of the blade, near the hilt) while katana usually have a more even curvature called chūzori or sometimes a sakizori type curvature, typical of uchigatana. These are the three main types of curvatures.
While there are also tachi with the handle curving slightly toward the pommel - a shape particularly associated with jintachi and still used by Japanese warriors until as late as Sengoku-jidai - the sharp S-shaped curvature associated with jintachi is purely fanciful and without any historical basis whatsoever.
Before the standardization of the dimensions of the katana, which took place during the Edo period, the tachi could have a nagasa ranging from 60 cm to 90 cm, beyond which it was called odachi or nodachi.
Thus, some koryu bujutsu schools foresee in their curriculum the handling of the odachi, such as the ancient Kage-ryu or the Koden Enshin-ryu, famous for the master Tanaka Fumon who handles swords measuring 90 cm or more.
The longest nodachi are titans with a nagasa greater than 2 m, often used as offerings for Japanese gods. Thus, the tarōtachi of Makara Naotaka, with a nagasa of 220 cm (for a weight of 4.5 kg).
Nenekirimaru, forged during the Nanboku-chō period, has a nagasa of 215 cm (blade length) and a zenchō of 324 cm (全長, total length).
A sword signed Ho Norimitsu measures 223.5 cm nagasa and has a zenchō of 377.6 cm: it can be used as a nodachi as well as mounted as a naginata. All three of these examples are odachi (although one can also speak of ō-ōdachi...) but they are not jintachi.