Kogarasu Maru - Blade Classification and History

Blade Classification and History

'Kissaki Moro Ha Zukuri' blades like the Kogasaru Maru are sometimes referred to as 'Kogarasu Zukuri', since the blade of the Kogarasu Maru is shaped this way and is well known for its distinctive sugata. The Kogarasu Maru is unique as a bridge between the old double-edged Japanese Ken (based on the traditional Chinese straight sword) and the traditional Japanese tachi and eventual katana.

The Kogarasu Maru was designed with a curved double-edged blade approximately 62.8 cm long. One edge of the blade is shaped in normal tachi fashion, but unlike the tachi, the tip is symmetrical and both edges of the blade are sharp, similar to a European sword or a Japanese yari spear, except for about 20 cm of the trailing or concave edge nearest the hilt, which is rounded. A single koshi-hi style groove runs from the nakago to the trasitionpoint where the blade becomes double-edged, and is invariably accompanied by a soe-hi. The yaki-ire (hardening) process yielded a sugaha hamon (straight 'temper' line) on both sides of the blade.

The Kogarasu Maru "Little Crow" is the most famous of the known Kogarasu Zukuri blades and is currently in the Japanese Imperial Collection. The tang of the Kogarasu Maru is not signed but the blade is believed to have been made during the either the early Heian period or late Nara period, by the sword smith Amakuni, who is said to have created the first curved Japanese sword and is believed to have lived during this period. Two other Kogarasu Zukuri blades exist from this era, but many other blades of this type have been created throughout Japanese history.