Aikuchi

The nihongo|aikuchi|合い口 or 匕首 (literally "fitting mouth") is a form of mounting for Japanese blades in which the handle and the scabbard meet without a guard in between. Originally used on the koshigatana (a precursor to the wakizashi) to facilitate close wearing with armor, it became a fashionable upper-class mounting style for tantō (daggers) in the Edo period. Small aikuchi tanto known as "kaiken" became popular with the Yakuza, as they were easy to conceal; however, the most typical user of "kaiken" were women samurai from the Edo period onwards, who kept it as an emergency and/or suicide weapon.

According to S. Alexander Takeuchi from University of North Alabama, Department of Sociology, aikuchi, is a form of koshirae (mounting style) which commonly was used in tanto creation. The nomenclature of the word "aikuchi" is the following: the " _ja. ai" is a gerund which means "meeting" and " _ja. kuchi" is a noun that means "mouth". The same formula is used in "koi-guchi". So, "aikuchi" initially was a style of mounting in which the "fuchi" meets with the "koi-guchi".

Later, in the Tokugawa period, this tradition of blade mounting gave the name to the very short samurai sword—tanto. Thus, the aikuchi tanto represented a no-tsuba (guard) short sword mainly used in Tokugawa period. The dagger was short and it had a cutting edge the length of which was about 9 inches. It could serve for self-defense as well as for attacking the enemy by throwing it. This weapon looks similar to tanto—the only difference is that aikuchi does not have a hand guard. It was very popular during fifteenth century.

Aikuchi was used mainly during infighting as well as close range grappling. It served for dispatching the enemy when thrown to the ground. This weapon can be easily recognizes by the size of its blade as well as by the fact that it had no hilt guard. Aikuchi was also created in a thicker version. The latter was called yoroi tōshi (Japanese for "armor piercer"). Yoroi tōshi was a strong dagger able to cut through armor when fighting at a close range.

There was also another type of aikuchi called moroha zukuri (Japanese for "double-edged style"). Its blade length was about 7 inches and its blade was sharpened on both sides. It is considered that the best aikuchi knives were created by the famous Japanese swordsmiths that represented the Osafune school, situated in Bizen province. Nowadays these daggers are considered to be very rare and thus very valuable.

Lucy Lui's character O-Ren Ishii in Quentin Tarantino's "Kill Bill" uses a black aikuchi-style katana sword.