The nodachi (野太刀) refers to a large Japanese sword. The characters (kanji) which are read "nodachi" mean "field sword". However, some have suggested that the meaning of "nodachi" closer approximates ōdachi (大太刀), or "large tachi". A confusion between the terms has nearly synonymized "nodachi" with the very large "ōodachi". Thus, while the original use of the term may have been to refer to any type of long battlefield sword (daito) such as a tachi, it currently is misapplied to any type of oversized Japanese sword.
The blades have the same general appearance and design of a tachi though they were significantly longer. The nodachi was carried by foot soldiers and was designed as a weapon for war versus cavalry and open field engagements. Nodachi were generally used on open battlefields as their length made their use indoors or close quarters difficult. They were an effective weapon against cavalry, though they were not commonly used. Nodachi were infrequently used for several reasons:
- The nodachi required greater strength to properly wield
- Weapons such as the naginata or nagamaki were arguably more effective for the same role on the battlefield.
Some illustrations show a samurai with a wakizashi (small blade), katana (medium blade), and Nodachi (large blade). It would have been highly unlikely to have actually seen a samurai with all three at the same time, however. Such illustrations were probably created to show size difference between the various blades. During times of peace the sword was worn slung across the back as a symbol of status. This is distinctive because most Japanese swords such as the katana, wakizashi, and tachi were worn at the waist or belt; however it was not "drawn" from the back. The nodachi was more difficult to wield due to its abnormal size and weight, but like any weapon, could be extremely deadly if the warrior wielding it was skilled. The size of the blade made the nodachi a fearsome weapon when wielded by a skilled warrior. The length of the nodachi's hilt varied between twelve to thirteen inches. Its cutting capability and range exceeded that of a katana, due to its weight and size. Legend says that a nodachi could cleave a warrior and his horse in half with a single blow. Only the strongest warriors were capable of using a nodachi single-handed.
In some Chinese martial arts, Pa Kua Chang being perhaps the best known example, oversized weapons are used for training purposes in order to condition the martial artist to handle a normal-sized weapon more efficiently (as is the case with the suburito, a training weapon).
The Kage Ryu (Shadow School) is maybe the only known ryūha still existant that uses the Japanese long-sword (which they call choken).