Nihonto Club

A way to preserve mei (signature) on the tang when shortening it (see o-suriage) by cutting it off the original position and reattaching it to the altered nakago.

See nagasa.

A distinct temper line between areas of softer (ji) and harder (ha) steel along the edge of the blade.

See Hamon Types for more details.

Hi is a groove engraved along the blade on the shinogi-ji or hira-ji area. Originally the main purpose of these grooves was to reduce the blade's weight and improve its cutting ability. Later grooves served as a decoration or even as a way to conceal flaws.

Grooves are classified according to shape and location with terms describing the top of the groove ending with -hi (樋, usually pronounced as -bi when preceded by other characters) or -tome (止め) for features at the bottom of the groove (known as tome).

Hi

• bo-bi: A continuous straight groove of notable width, known as katana-bi on tantō. With soe-bi, a secondary narrow groove follows the inner straight length of the main one. With tsure-bi, the secondary is similar but continues beyond the straight length.
• kage-bi: A small groove beside a regular groove of a blade. Yamanaka mentions that this was an old term for soe-bi.
• futasuji-bi: Two parallel grooves.
• shobu-bi: A groove shaped like the leaf of an iris plant.
• naginata-bi: A miniature bo-bi whose top is oriented opposite from the blade's, and usually accompanied by a soe-bi. Seen primarily on naginatas.
• kuichigai-bi: Two thin grooves that run the top half of the blade; the bottom half is denoted by the outer groove stopping halfway while the inner one expands to fill the width.
• koshi-bi: A short rounded-top groove found near the bottom of a blade, near to the tang.

Tome

• kaki-toshi: The groove runs all the way down to the end of the tang.
• kaki-nagashi: The groove tapers to a pointed end halfway down the tang.
• kaku-dome: The groove stops as a square end within 3 cm of the tang's upper end.
• maru-dome: Similar to the kaku, except with a rounded-end.

The Tokugawa Shogunate standardized the size of swords in Japan during the Edo period to what is commonly called jōsun length. For katana jōsun is 2 shaku 3 sun 5 bu (71.21cm), for tantō - 8 sun 5 bu (25.76cm).

Tantō longer than jōsun are called sunnobi-tantō 寸延び短刀, and less than jōsun sunzumari-tantō 寸詰まり短刀. There was no standard length for wakizashi, but those over 1 shaku 8 Sun (54.5 cm) are called ō-wakizashi 大脇指. Tachi 太刀 of more than 3 Shaku (90.9 cm) are referred to as ōdachi 大太刀, whereas tachi under 2 shaku (60.6 cm) are called Kodachi 小太刀.

Source

Thickness of the blade. See also: moto-kasane, saki-kasane.

'Sword-shaped'. Shape of the nakagojiri with two straight lines coming to a point in the center at around 90 degree angle.

It is often seen among works of Masamune and his school, and Shinto swords made in Soshu tradition.

The part of the shinogi that runs from the yokote to the tip in the kissaki.

The notches dividing the blade proper from the tang. The notch on the blade side is called hamachi; that on the mune side is known as the munemachi.

The width of a blade measured from the mune to the cutting edge. See also: moto-haba, saki-haba.

Blade length, measured from the tip to the munemachi.

The end of the nakago.

A "greatly shortened" nakago. The o-suriage nakago is formed from the part of the blade (originally), while suriage nakago is more just reshaped. In this case the signature is usually lost, unless orikaeshi-mei or gaku-mei have been performed.

The shaku is an archaic Japanese unit of length which is commonly approximated to be 12 inches (1 foot). As with other measurements, it was originally derived from nature: the average length between nodes on bamboo. Since 1891, the shaku has been defined to equal 10/33 meter (approximately 30.3 cm, or 11.93 inches), or 3.3 shaku to the meter. A single shaku is divided into 10 sun (寸).

1 shaku = 11.93 inches (30.30 cm)

1 shaku = 10 sun
1 sun = 1.193 inches (3.03 cm)

1 sun = 10 bu
1 bu = 0.119 inches (0.303 cm)

1 bu = 10 rin
1 rin = 0.01193 inches (0.0303 cm)

Shorter than average (see jōsun) wakizashi or tanto.

Blades which weren't shortened (still have nakago in its original shape) can be referred to as 'ubu'.