Futokorogatana (懐刀) is translated as “clothing fold sword” and describes a type of tanto mounting meant to be carried in the kimono sleeve or fold. Also known as kaiken, this humble style of hidden mounting is usually unadorned with a smooth profile and lacquer finish. This knife would historically be carried for last chance survival situations.
The blade began as a reclaimed piece of horse-drawn carriage spring and was hand forged in a charcoal fire, smoothed with files and a sen scraper, differentially hardened using traditional water quench yaki-ire, and polished by hand with natural Japanese water stones.
Materials for the kaiken style koshirae mounting include Japanese hounoki wood for the handle and scabbard, copper bus bar for the habaki, washi paper, and benigara (crimson lake) stone powder mixed with natural urushi lacquer and crushed tea leaves, and a reclaimed hardwood chopstick for the mekugi.
The kaiken tanto was designed to be carried in the fold of a kimono and is characterized by a smooth profile and unadorned lacquered exterior.
Blade construction is muku with a hira-zukuri profile and an iori mune. There is a small ~1mm kizu in the boshi on the omote side. The blade is just under 4″ long, overall length is just under 8″, and the overall length when sheathed is about 8.5″.
長さ/刃長 Nagasa: 3 sun 3 bu 4 rin (101mm)
元幅 Motohaba: 6 bu 3 rin (19.5mm)
重ね/元重 Motokasane: 1 bu 8 rin (5.1mm)
反り Sori: uchizori
中心/茎 Nakago: 2 sun 8 bu 4 rin (86mm)
柄長 Tsuka: 2 sun 8 bu 5 rin (87mm)
拵全長 Koshirae: 7 sun 2 bu (218mm)
形 Katachi: hira-zukuri, iori-mune
刃文 Hamon: suguha
帽子/鋩子 Boshi: ko-maru
中心/茎 Nakago: futsu, kuri-jiri, one mekugi-ana, signed near the tip
銘 Mei: hot stamped katabami-ken kamon
拵 Koshirae: kaiken, issaku
Material: Reclaimed antique carriage spring steel, copper bus bar, Hounoki, natural urushi with benigara and tea leaves, reclaimed hardwood from a chopstick
This piece is in a private collection in San Antonio, Texas.
scroll down or jump to the sections below, more information here:
Forging the Blade
Making the Habaki
Carving the Tsuka & Saya
Making a Mekugi
= 0.1 shaku（尺）
= 1 sun（寸）
= 10 bu（分）
= 100 rin（厘）