Chokutō
The chokutō (直刀 is a type of Japanese sword that dates back to pre-Heian times. Chokutō were made in later periods, but usually as temple offering swords. Chokutō were straight and single-edged (sometimes partially double). It is believed that chokutō were imported to Japan from other Asian countries such as China and Korea.
Chokutō was among the earliest in the history of Japanese sword forging. It was created before the differential tempering technology evolved. Chokutō typically come in hira-zukuri and kiriha-zukuri tsukurikomi (blade styles) which make them very distinct from later tachi and katana which rarely use these forms. The main distinctive feature of the chokutō is the blade, which is curved on the katana sword and straight on the chokutō. Its blades are also often confused with shikomizue. Very few examples of chokutō mountings remain and there is little evidence to suggest that they were ever mounted as cane swords.
Chokutō was less effective against other swords which were lighter and had curved blades. This is why the samurai culture turned towards a sword with a curved blade so they could protect their daimyo. Later, several talented swordsmiths learned special techniques to improve the blade of the chokutō sword. They made it more resistant and at the same time kept its original straight shape.
Despite the fact that chokutō is not very useful in battle, many warriors considered it an excellent way to test their skills when struggling against curved blade swords. Its tip is curved and it is delimited by a ridge, which is perpendicular to the blade.