National Treasures & Important Cultural Properties
of National Institutes for Cultural Heritage, Japan

　Swords created before the Keicho era (1596 to 1615) are called koto (old swords), while those made after the era are called shinto (new swords). Osuminojo Masahiro was the best disciple of Horikawa Kunihiro, the founder of the shinto forge. Kunihiro, a swordsmith of Hyuga no Kuni, later lived in Ichijohorikawa, Yamashiro no Kuni and trained many disciples. Masahiro was also from Hyuga no Kuni and lived in Horikawa, Yamashiro no Kuni, but very few of his works remain. This sword has a wide blade with an overall shallow curve, a typical characteristic of the blades of the early Edo period. The jigane (ground metal) shows a combination of itamehada (a wood grain pattern) and mokumehada (a round wood grain pattern) with thick jinie (small martensite crystals in the ground) and chikei (curved lines of martensite crystals in the ground). The hamon (blade pattern) has a combination of leisurely notareba and gunomeba patterns with nie (small martensite crystals) and kinsuji (small shiny lines). His jigane and hamon clearly reflect his master's style.