A chokutō (直刀, lit. "straight sword") is an uncurved straight Japanese sword produced before the tenth century.
Chokutō are used on foot for stabbing or cutting and are worn hanging from the belt.
History of Chokutō
Chokutō are among the earliest in the history of Japanese swordsmanship. They are created before the development of differential tempering in Japanese sword forging.
Chokutō usually come in hira-zukuri and kiriha-zukuri tsukurikomi (blade styles) which makes them very distinct from later tachi and katana which rarely use these shapes.
The distinctive feature of the chokutō is the straight blade, similar to ancient swords found in the Three Kingdoms period of China. Its blades are often confused with those of shikomizue, there is little evidence to suggest that chokutō were ever mounted as a cane sword.
Although curved blades are as old as the sword itself, they did not spread to Asia and the Middle East until after the domination of the Mongol Empire.
Japanese warriors of the Kamakura shogunate experienced firsthand the effectiveness and lethality of curved blades during the Mongol invasions of Japan.
The crude forms of what would become the tachi gradually begin to eclipse the chokutō in popularity while curved blades demonstrate greater ease of handling and lethality in mounted combat.
Decline of Chokutō
Kofun period chokutō like swords of other periods relied on the weight of the blade in execution rather than thrusting attacks.
The advent of the katana design with its single-edged blade curve and superior metallurgy allows for the development of specialized fencing techniques such as the iaidō.
Very few examples of chokutō mounts remain, enough however to reconstruct their various typologies which still follow Chinese and Korean patterns;
this is evident with one of the last sword designs developed during the Kofun period, the single-edged warabitetō (蕨手刀).