The Soshu (also called Sagami) tradition was established by Shintogo Kunimitsu in the late Kamakura period. His known swords with inscribed dates show that he was active at least between 1293 and 1334 AD. Kunimitsu's Hamon are Suguha in Nie, his Jihada is rich in Ji-nie with swirling Itame forming Kin-suji. Among his pupils were two of the most famous names among Japanese swordsmiths: Yukimitsu and Masamune.

Masamune had enormous influence on swordmaking throughout the country. His success was in part due to the fact that he carefully selected his iron, forging together different kinds of steels to give improved strength and hardness. He also successfully tempered blades at a higher temperature than anyone before him, resulting in brilliant Nie. The high temperature usually causes the blade to become extremely hard and brittle; however, he is also credited with "inventing" stress relief, thus avoiding those undesired effects.

The Jigane is complex with varied hues in the Jihada, rich in Ji-nie, with both bright and dark pools of Chikei. The Hamon is predominantly Notare with Midare-ba, deep and intense with varied lines of Inazuma, Sunagashi and Kinsuji. The effect is not unlike the work of Yasutsuna of Hoki in its extremes of activity, and it is thought that Masamune may have consciously emulated him.

Although Masamune worked mainly during the Kamakura period (1185 - 1333 AD) when one of the characteristics of swords was the pronounced tapering down of the width towards the point, Chu-kissaki and Koshi-zori or deep Torii-zori, he also produced swords at the beginning of the Nambokucho period (1333 - 1392 AD) and consequently we see swords of him with an overall wide Mihaba, shallow Torii-zori and O-Kissaki.

Because blades actually signed by Masamune are exceedingly rare, a theory was developed at the end of the 19th century that Masamune never existed at all. In the sword books of the Muromachi period the scarcity of signed blades by Masamune is accounted for by the explanation that his work was so absolutely distinctive that there was no need for a Mei. However, it is more likely that the reason lies in the fact that Masamune was employed by the Kamakura Bakufu (administration); many of his swords were made for the use by the Shogun, and it would have been presumptuous and contrary to all normal practice - at that time - for him to have signed them. Another reason is simply that Tachi were of such great length that they have been cut down to a convenient size for wearing in Uchi-gatana - koshirae, and have therefore lost the inscriptions that were on the original Nakago.

A number of signed Tanto are extant which are demonstrably by the same hands. Those blades that still retain his signature are inscribed with two characters - MASA MUNE - except the Tanto "Daikoku Masamune" that bears the signature "Masamune Saku". Masamune is perhaps the most famous of all Japanese smiths. The distinguished scholar and statesman Kanera Ichijo (1402 - 1481 AD) recognized Masamune as one of the great men of modern times, and praised him as a smith whose blades were equal in quality to the sharp weapons of the Buddhist guardian deity Fudo himself. Masamune's Hamon is usually described as refined and leisurely at the same time, his Kinsuji looking like lightning in the clouds, and his Nie like bare patches in partially melted snow.

Of the many skilled individual smiths of the Muromachi period (1392 - 1573 AD) Muramasa of Ise deserves particular mention. It seems there were three generations of smiths signing Muramasa; their work is similar to that of Heianjo Nagayoshi - and Kanesada of Seki, who worked in Mikawa and Yamada of Ise respectively, whose blades, like Muramasa's are reputed to cut well. Muramasa of Ise's work contains much of both Soshu and Mino traditions. The Jigane is often whitish, like the work of Kanesada and other good Mino smiths. His Hamon varied considerably and included Notare, Gunome, and his own particular variant of Sanbon-sugi.

Shogun Tokugawa Ieyasu's grandfather was slain at age 25 by a Katana made by Muramasa, his father received a serious wound by a drunk with a Wakizashi made by Muramasa, and he himself cut his hand with a Kogatana by Muramasa. As Muramasa's work was considered unlucky for the Tokugawa family, various prohibitions were imposed by the Tokugawa Bakufu regarding the carrying of his swords. But since Muramasa's swords were considered extremely good cutters, the character MURA, was sometimes obliterated, and the character MUNE inscribed beneath the remaining character MASA, thus transforming the Mei into the far more palatable Masamune. It might have been this practice that gave rise to the popular belief that Muramasa was a pupil of Masamune of Soshu, yet his earliest-known work is dated 1501 AD, almost two centuries after Masamune's time.

There are quite a few legends surrounding Masamune and Muramasa and their blades. Masamune's work was considered benign, and Muramasa's evil and bloodthirsty - Katsujinken (life-giving sword) and Satsujinken (life-taking sword). The most popular story has two swords - a Masamune and a Muramasa - were held into the water of a gently flowing river. The autumn leaves floating by drifted away from the Masamune, while they were drawn to the Muramasa and cut in pieces. Although the stories are quite entertaining, they are just myths. Collectors appreciate these swords for their artistic, cultural and historic value and significance, not for the folklore surrounding them.


References:

The Japanese Sword by Kanzan Sato
Swords of the Samurai by Victor Harris & Nobuo Ogasawara
Nihonto Koza Vol. IV