Katana is developed in Japan, and it is a traditional Japanese sword. It was used by the samurai of ancient and feudal Japan. Katana has a very distinctive appearance, it is a curved, single-edged blade with a circular or squared guard, with a long grip, where you can put both hands. Katana was the finest cutting weapon in world military history.
Katana is the weapon which is not used only in one martial art, but in few of them. This is probably the most important weapon, and almost everybody has heard of katana. It is important to mention that this kind of weapons are not used as a purpose to hurt somebody, but only for self-defense and for improving training skills. Here is a list of martial art in which katana is used.
The most common use of katana today is in kendo. A lot of people, who think about kendo, think about shinai. But that is a mistake because kendo as a weapon uses katana. Kendo traditionally takes the same place as kenjutsu as the way to teach swordsmen and swordswomen the reality of combat. Kyu-grade kendoka will also tell you that fighting is messy, complicated and not as simple as what you see in kata. The purpose of Kendo from the Meiji period till the World War II and after was to provide a martial arts environment to experience something as close to real combat as possible, but also a well- rounded experience.
Kendo and Iaido are similar forms of martial arts; they are both focused on swordsmanship at the initiation of an engagement. If you are drawing from a seated position against a single target, or you are standing and matched against multiple targets with your sword, Iaido is focused on how to engage someone with your katana on the draw. Iaido today is a mix of several very popular styles of swordsmanship.
Toyama- Ryu is the last school of Japanese martial arts that taught their students on how to use weapons to kill people. Today, of course, weapons are not used for that purpose. Toyama-Ryu was created by the Imperial Japanese Army for their solders. They taught them how to defend themselves and fight during the Sino-Japanese War, but also World War II. This martial art uses katana, but also the bayonet. Katana was taught to officers, and the bayonet forms were used by rank and file. Toyama- Ryu is a relatively modern martial art, developed as a result of the IJA’s desire to reincorporate the katana in battles like Sino- Japanese War. The people who trained Toyama- Ryu have largely lived in the 20th century and passed their knowledge through living students in Japan and the US. This makes Toyama- Ryu slightly popular than other martial arts.
Iaijutsu is focused on the same things as Iaido. But unlike Iaido, Iaijutsu is not single martial art and has many different styles of using katana. It is intended to be used mostly by students.