Japanese swords can be roughly categorized into four types based on their length: "Tachi," "Katana," "Wakizashi," and "Tanto." These four types were the standard weapons used by Japanese warriors. In addition to these four types, there were also other weapons such as "Naginata" (a polearm), "Tsurugi" (a double-edged straight sword), and "Yari" (a spear).

Throughout Japanese history, there were also names for swords like "Odachi" (large sword), "Tsurugi" (straight sword), "Naginata" (long-handled sword), and "Koshigatana" (waist sword), among others. However, these names were later replaced by other designations.

Tachi

Tachi is the earliest form of Japanese sword and is generally longer. It was used for cavalry combat or commanding purposes. The blade of the Tachi has a large curve, and the hilt is often slightly curved upward.

Among the different types of warrior swords, the most numerous were the "Katana," but the most valuable one was the "Tachi." This is because, from a physics perspective, the slightly backward tilt of the blade allows it to utilize the principle of "arc continuity" better than the upright style. In other words, the Tachi can demonstrate the maximum cutting range at various angles, making it more suitable for use by mounted warriors. Additionally, in terms of length and weight, the Tachi surpasses the other four types, which means that the more force wielders exert, the more they can fully unleash its characteristics of "maneuverability" and "peerless sharpness."

The "Kebi Tachi" is a ceremonial sword not used in actual combat. It is also hand-forged, with a more curved, long, narrow, and thin blade. It holds significant artistic and craftsmanship value.

Katana (Uchigatana)

The Uchigatana, commonly referred to as the "Katana", is the most prevalent form of Japanese warrior sword. It appeared much later than the Tachi and first emerged in the 14th century, reaching its peak popularity in the 15th century. The Katana was mainly used by infantry and, therefore, is slightly shorter than the Tachi with a smaller curve. When sheathed, the edge faces upward, and when used, drawing and slashing at the enemy are accomplished in a single motion.

Wakizashi

The length of the Wakizashi falls between 30 to 60 centimeters. It is similar in appearance to the Katana and is used for close combat situations.

Tanto

The Tanto has a blade length of fewer than 30 centimeters and was carried by higher-ranking samurai as a personal weapon.

Yari (Spear)

The Yari is the Japanese version of a long spear. Common types include "Oo-yari" (large spear), "Hiraisen-yari" (spear with a flat blade), "Juji-yari" (cross-shaped spear), and "Chidori-yari" (plover-tailed spear), among others.

Naginata

The Naginata, originally used for cutting and mowing, is a long-handled Japanese sword with a shaft length of about 200 centimeters. It can be used both on horseback and by infantry, but its effectiveness is more pronounced when used while mounted.