The nodachi (????) 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 odachi (?????), or "large tachi". A confusion between the terms has nearly synonymized "nodachi" with the very large "odachi". Thus, while the original use of the term may have been to refer to any type of long battle field 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 blade was more difficult to forge compared to a "normal" sized sword
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.
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 were skilled. The size of the blade made the nodachi a fearsome weapon when wielded by a skilled warrior. Its cutting capability and range exceeded that of a katana (due to its weight and size) and therefore the nodachi can probably be considered to be the most powerful sword ever made if cutting capability is any measure of a sword's power. It has been said that a nodachi could cleave a warrior and his horse in a single blow. In some Chinese martial arts, Pa Kua Chang being perhaps the best known example, oversize weapons are used for training purposes in order to condition the martial artist to handle a normally sized weapon more efficiently.

The Kage Ryu is maybe the only known ry??ha still extant that uses the Japanese long-sword (which they call choken).