Tanto - Japanese Short Blade

The Tanto (short blade, also known as the Aikuchi) is as it's name implies the shortest of Nihonto (traditional Japanese blades). The blade of the Tanto is on average around 6 to 8 inches long with the handle being around 4 to 5 inches. It is taught to some degree in most forms of Kenjutsu and Budo/Bujutsu and due to its easily concealed size is utilised to great effect in Ninjutsu techniques.

Like it's bigger brothers the Wakazashi and Katana, the Tanto can be used to parry attacks from other blades but is best suited for 'in close' combat situations (traditionally on the battlefield for finishing of a vanquished opponent as it was much more suitable for slipping beneath vulnerable spots in Samurai armour). Like the slightly longer Wakazashi, the Tanto is also ideal for use in confined areas such as indoors, or dense forests or anywhere where it is impractical to swing a longer weapon such as the Katana.

The Tanto was also notoriously the weapon of choice for failed or disgraced Samurai to use to commit seppuku or as it also known Hara kiri (literally belly cutting) which was a form of ritual suicide (not as common as is portrayed in Samurai movies nowadays but nevertheless did take place).
In recent times (mid 80's and onwards) the name Tanto has become synonymous with a type of tactical/utility knife that has little to do with the traditional form of the weapon but is more like a miniature version of the (controversial) straight bladed Ninjato. These knifes tend to be smaller than traditional Tanto and most lack the traditional fittings of the classical Nihonto version.

Reference Sources

1. Tanto picture created by Nathan Hiemenz [Public domain], via Wikimedia Commons, https://commons.wikimedia.org/wiki/File:Tanto_blade_plus_scabbard.jpg, Added - 04/15/15