Tanto in Shirasaya with Koshirae (NBTHK Hozon paper)
Signature : Gassan
(We divide 4 sections for each sword as Saijo saku, Jojo saku
Jo saku and regular saku)
This Gassan belongs to Jojo saku ranking.
The blade is polished.
Habaki : Silver double Habaki.
Blade length : 23.2 cm or 9.13 inches.
Sori : 0 cm or 0 inches.
Mekugi : 1
Width at the Hamachi : 2.06 cm or 0.81 inches.
Kasane : 0.63 cm or 0.24 inches.
Era : Middle Muromachi period.
Shape : The blade is regular size width and thickness with long nakago.
Jitetsu : Ayasugi-hada well grained with Jinie attach and Utsuri like a stick appear on surface of the blade.
Hamon : Hamon starts as Niedeki double style, and then become active wild feeling from Monouchi to Kissaki.
Special feature : Ko-Gassan school were active at Mt. Gassan in Dewa province during Kamakura to mid Muromachi period. This school disappeared at the end of Muromachi period.
But at later Edo period, Gassan Sadakazu researched Ko-Gassan forging technique well and resurrected Ko-Gassan Ayasugi-hada blades and kept secret only for his lineage.
Ko-Gassan blades are having wild feeling and the blades froged by Sadakazu becomes more elegant styles.
The famous Ko-Gassan school swordsmith are Gunsho, Chikanori and Hisatoshi.
Most of blades with signature remaining are having just two characters, the moon and the mountain, probably for the religion meaning.
Koshirae : Aikuchi Koshirae
Menuki : An ear of rice carved on Shakudo plate with gold color.
Saya : Black Roiro-Saya with some design like Shishi-dog carved on iron fitting.
NBTHK Hozon paper
Aoi Art estimation paper : whole Oshigata.