Double-Edged Japanese Swords: 4 Major Types and Their History

Like many other cultures globally, Japanese double-edged swords were the first type of blades made before evolving to the slightly curved single-edged blades as seen in the katana and wakizashi today. 

In this article, we traverse through time to examine the different types of double-edged Japanese swords, their history, characteristics, and how they evolved to the version we know today.

1. Tsurugi

One of the first types of Japanese swords was the tsurugi, also known as ken. Like many first blades of the world, the tsurugi has double-edged blades with a fairly acute tip. While likely inspired by the Western-influenced Chinese jian, it could have been created simply by strengthening and elongating shorter ceremonial or daily utilitarian daggers.

The tsurugi was a battle-ready short sword used in combination with shields in battle, way before the Japanese samurai existed. The earliest specimens were dated around the 2nd century BCE, but the design could have existed even prior to that time. 

These swords are believed to be used as ceremonial blades that are used in early Japanese traditions, such as the Shinto religion. With time, tsurugi swords were replaced by single-edged blades.

2. Warabiteto

The warabiteto, sometimes called wanto, is a Japanese sword that usually has straight blades and some will have a very slight curve. Believed to be one of Japan’s first single-edged blades, they are thought to be inspired by early Western Chinese zhibeidao or individually crafted as a sword that’s easier to produce and maintain.

On average, the warabiteto are fairly short, similar to a larger tanto, but some longer ones have the dimensions of a short sword. While most surviving specimens were found to have a  single-edged blade, around 5% featured a double-edged tip.

Due to the above findings, some experts believe that these blades could be the first to spur the evolution to curved single-edged swords which were very popular among the mysterious Emishi people in the northeastern parts of Japan.

3. Kogarasu-Maru

The Kogarasu-Maru is a unique tachi sword with a curved double-edged blade, except for the rounded 7.87 inches (20cm) segment on the concave edge nearest the hilt. Believed to have been created around the 8th century or later, there are multiple theories such as it being a gift from Korea or produced in China, making it the possible link between the earlier straight blades and the later curved ones that emerged during the Heian period (794-1185).

Sometimes the curved double-edged Japanese sword is called a “three-legged crow” or crow blade. This comes from the legend that the kogarasu maru was crafted by Amakuni, a legendary swordsmith and delivered to the emperor Kanmu (781-806 CE) by a giant crow.

These swords could be the result of combining the single-edged Chinese dao with the warabiteto. Featuring steel blades that undergo differential clay tempered heat treatments, this produces a hamon (temper line). 

4. Kissaki-Moroha-Zukuri

With the earlier double-edged swords having left a mark on future samurai swords, some historical and even modern katana swords feature a double edge as well. These high quality swords are usually forged from high-carbon steel and can be used in Japanese kenjutsu (sword martial arts). 

Today, despite being popularly called the double edge katana, it is also used in other swords such as the wakizashi, larger odachi, and even in tanto.

History and Evolution of Japanese Double-Edged Blades

Double-edged blades used in battle around the 10th century BCE to the 10th century CE are called Jokoto (ancient swords) which were used in practice and battle. Those that entered the next era are known as Koto (old swords), but these were mainly ceremonial double-edged blades. Since most of the blades throughout the Japanese archipelago were either inspired or influenced by Korean and Chinese swords, the history of Japanese swords begins there.

In fact, even the earliest bronze sword found in the Japanese archipelago is a Chinese-style jian dagger dating to the 9th century BCE, while the earliest iron sword in the region- the Tōdaijiyama Sword is yet again Chinese, dating to the 2nd century CE. These were obtained as a result of diplomatic missions or ceremonial gifts. Inspired by the design of the Chinese jian, the first Japanese sword (tsurugi) emerged with a double-edged blade larger than that of a shorter knife or dagger.

When the battle-effective straight single-edged dao appeared in China during the Han Dynasty (202 BCE – 220 CE), single-edged blades also appeared throughout the Japanese archipelago. While initially similar to the dao, the design evolved to become the Japanese chokuto, often mistaken today as the Holywood-ninjato used by the ninja.

When the missions and diplomatic ties between China and Japan fell apart with the end of the Tang Dynasty (618 – 907 CE), this was a significant time in history as designs like the tang dao replaced the iconic Chinese double-edged jian. The single edged design became even more popular with the Mongol invasion (1274-1281) that introduced curved dao-like sabers.

Due to these diplomatic interruptions, Japan started crafting their own swords, giving rise to single-edged blades like the tachi and katana. These blades remained the main sidearm in a daisho set as it is easier to unsheath and is excellent on horseback.