Kaiken

A kaiken (懐剣^?) is a 20–25 cm (8–10 in) long, single or double-edged dagger without ornamental fittings housed in a plain mount.

It was once carried by men and women of the samurai class in Japan. It was useful for self-defense in indoor spaces where the long blade katana and intermediate sword wakizashi were inconvenient. Women carried them in their kimono either in a pocket-like space (futokoro) or in the sleeve pouch (tamoto) for self-defense and for ritual suicide by slashing the veins in the left side of the neck. When a samurai woman married, she was expected to carry a kaiken with her when she moved in with her husband.

Prior to modern orthographic reform the kaiken is now called Kwaiken kwaiken (pocket knife). The modern term and has no reference in historical records; also called a futokoro-gatana

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