Tanto Dagger (signed Sadayoshi of Takaichi, dated 1324; known as Kuwayama Hosho)

A Masterpiece of the Yamato Hosho School

The Tanto Dagger (signed Sadayoshi of Takaichi, dated 1324; known as Kuwayama Hosho) (短刀〈銘高市□住金吾藤貞吉／□亨〈二二〉年〈甲／子〉十月十八日〉（名物桑山保昌）) is a Kamakura-period tanto by Sadayoshi of the Yamato Hosho school, location not disclosed (private collection), which in 1955 was designated a National Treasure.

The Agency for Cultural Affairs records one blade 25.7 centimetres long with no curvature, 2.5 centimetres wide at the base and a tang of 10.5 centimetres, dated 1324, first designated under the old system in 1931.

According to the Agency, it is listed in the Kyoho register of famous swords and named Kuwayama Hosho after its owner Kuwayama Motoharu; it was handed down in the Maeda family.

The Blade

According to the Agency, it is flat-sided with a three-faced back, thick and unbending, sturdily made. The steel shows a well-ordered straight grain with ample crystals. The temper line is a gentle wave mixed with half-circles near the collar, growing stronger in crystals and golden streaks towards the tip, where the tempered area widens.

A sword motif is carved on the front and a groove on the back, both deeply cut. The tang is unaltered, with a straight end, crosshatched file marks, two peg holes, the signature on the front and a date on the back.

What to Look For

The Agency explains that the Hosho school lived in Takaichi District of Yamato, beginning with Kunimitsu in the mid-Kamakura period, whose son was Sadayoshi; several of Sadayoshi's works record where and when they were made, as this one does.

The Agency praises its orderly straight grain, typical of the Hosho school, and the way the tempered area widens and the crystals grow fiercer from base to tip.

Visiting the Tanto Dagger (signed Sadayoshi of Takaichi, dated 1324; known as Kuwayama Hosho)

It is privately owned and its location is not disclosed; no official information on viewing could be found.