Tameshigiri

Tameshigiri (試し斬り, 試し切り, 試斬, 試切) is the Japanese art of target test cutting. The kanji literally mean "test cut" (kun'yomi: ためし ぎり tameshi giri). This practice was popularized in the Edo period (17th century) for testing the quality of Japanese swords. It continues to the present day, but has evolved into a martial art which focuses on demonstrating the practitioner's skill with a sword.
During the Edo period, only the most skilled swordsmen were chosen to test swords, so that the swordsman's skill was not questionable in determining how well the sword cut. The materials used to test swords varied greatly. Some substances were wara (藁; rice straw), goza (茣蓙; woven rush mats) or tatami-omote (畳表; the top layer of tatami mats), bamboo, and thin steel sheets.
In addition, there was a wide variety of cuts used on cadavers and occasionally convicted criminals, from tabi-gata (ankle cut) to O-kesa (diagonal cut from shoulder to opposite hip). The names of the types of cuts on cadavers show exactly where on the body the cut was made. Older swords can still be found which have inscriptions on their nakago (中心) (tang) that say such things as "5 bodies with Ryu Guruma (hip cut)". Such an inscription, known as a tameshi-mei (試し銘) or saidan-mei (裁断銘) (cutting signature) would add greatly to a sword's value, compensating the owner somewhat for the large sums of money typically charged for the test.
Aside from specific cuts made on cadavers, there were the normal cuts of Japanese swordsmanship, i.e. downward diagonal Kesa-giri (袈裟斬り), upward diagonal (Kiri-age (切り上げ) or Gyaku-kesa (逆袈裟)), horizontal (Yoko (横) or Tsuihei), and straight downward (Jōdan-giri (上段斬り), Happonme (八本目), Makkō-giri (真向斬り), Shinchoku-giri (真直切り), or Dotan-giri (土壇切り)).
There is an apocryphal story of a condemned criminal who, after being told he was to be executed by a sword tester using a Kesa-giri cut, calmly joked that if he had known that was going to happen, he would have swallowed large stones to damage the blade.
During the Sino-Japanese War and World War II, Japanese officers routinely tested their new swords on captured Allied soldiers and Chinese civilians. Lieutenants Mukai and Noda held a competition to see who could behead 100 people fastest using a katana. The story was spread by only one Japanese newspaper, the Mainichi Shimbun in 1937. Tokyo District Court Judge Akio Doi in charge of judging the matter in Japan later said, "The lieutenants admitted the fact that they raced to kill 100 people. We cannot deny that the article included some false elements and exaggeration, but it is difficult to say the article was fiction not based on facts."
In modern times, the practice of tameshigiri has come to focus on testing the swordsman's abilities, rather than the sword's cutting capability. The swords used are typically inexpensive ones.
Practitioners of tameshigiri sometimes use the terms Shitō (試刀, sword testing) and Shizan (試斬, test cutting, an alternate pronunciation of the characters for tameshigiri) to distinguish between the historical practice of testing swords and the contemporary practice of testing one's cutting ability. The target most often used is the tatami "omote" rush mat. To be able to cut consecutive times on one target, or to cut multiple targets while moving, requires that one be a very skilled swordsman.
Targets today are typically made from goza, the top layer of the traditional tatami floor covering, either bundled or rolled into a cylindrical shape. They may be soaked in water to add density to the material. This density is to approximate that of flesh. Green bamboo is used to approximate bone.
Once the goza target is in this cylindrical shape, it has a vertical grain pattern when stood vertically on a target stand, or horizontally when placed on a horizontal target stand (dotton or dodan). This direction of the grain affects the difficulty of the cut.
The difficulty of cuts is a combination of the target material hardness, the direction of the grain of the target (if any), the quality of the sword, the angle of the blade (刃筋; hasuji) on impact, and the angle of the swing of the sword (太刀筋; tachisuji).
When cutting a straw target that is standing vertically, the easiest cut is the downward diagonal. This is due to a combination of the angle of impact of the cut against the grain (approximately 30-50 degrees from the surface), the downward diagonal angle of the swing, and the ability to use many of the major muscle groups and rotation of the body to aid in the cut.
Next in difficulty is the upward diagonal cut which has the same angle, but works against gravity and uses slightly different muscles and rotation. The third in difficulty is the straight downward cut, not in terms of the grain but in terms of the group of muscles involved. The most difficult cut of these four basic cuts is the horizontal direction (against a vertical target) which is directly perpendicular to the grain of the target.
Historical European Martial Arts reconstructors, under the term "test cutting", engage in similar exercises with various European swords. While goza, green bamboo (though rarely), and meat are the preferred cutting targets, other substances are commonly used due to being cheaper, and much easier to obtain: pool noodles, various gourds (pumpkins, squash, etc.), water-filled plastic bottles, soaked newspaper rolls, synthetic targets or wet clay.
Many world records have been achieved with the katana which are certified by the Guinness World Records.
The targets can be placed in different configurations: