AS25137 Katana：Mumei (Sekishu Naotsuna)(66th NBTHK Juyo Token)

Katana in Shirasaya (66th NBTHK Juyo Token)

Signature: Mumei (Sekishu Naotsuna)
無銘(石州直綱)

Chu-koto: Jyojyo Saku: Iwami
(We divide 4 sections for each sword as Saijyo Saku, Jyojyo Saku, Jyo Saku and Regular Saku.)
This work is ranked as Saijyo Saku among the Mumei (Sekishu Naotsuna) blades.
Habaki: Silver foiled single-layered
Blade Length: 70.9 cm (27.91 in)
Curvature: 1.5 cm (0.59 in)
Mekugi Hole: 3
Width at Base (Motohaba): 3.02 cm (1.19 in)
Width at Tip (Sakihaba): 2.12 cm (0.83 in)
Thickness of Rim (Kasane): 0.7 cm (0.28 in)
Sword Weight: 690 g
Era: Nanbokucho period, around Kakei era (circa 1387)
Shape:An O-suriage Mumei blade with a wide mihaba and well-proportioned shape.
Jigane:The hada is a mix of itame and mokume, demonstrating well-forged and high-quality jigane.
Hamon:　Ko-nie-based gunome midare with a deep nioiguchi, displaying a soft and elegant pattern. Sunagashi and kinsuji are clearly visible within the ha. The boshi is midare-komi with a double blade (nijuha) at the tip, sweeping in a hakikake style

Features: The first-generation Sekishu Naotsuna was the son of Moritsuna and was commonly known as Kyuemon. He is recognized as one of the Juttetsu of Masamune and is locally referred to as Dewa Masamune. His residence was in Dewa, which is now part of Shimane Prefecture.
In the 66th Juyo Token, this blade is considered to have the finest hamon among the works of Sekishu Naotsuna.

Aoi Art’s Comment: I have never seen such an excellently crafted hamon from Sekishu Naotsuna. The nioiguchi is deep, with sunagashi and kinsuji activity inside the blade. The boshi features double and triple lines, creating a splendid and vibrant work. The jigane is also well-forged, with plenty of chikei, making it particularly recommended for those who appreciate the Soshu-den tradition.

66th NBTHK Juyo Token
Aoi Art estimation paper: Whole Oshigata