Previous answer is
Mumei (unsigned) (Ko Kongo Hyouei)

Special feature : Ko Kongo Hyoei school was working at Kamakura period to Nanbokucyo period. This sword is very wide and long gorgeous shape.
Jigane is quite well grained with item had and oo item had mixed well grained.
The blade with accompanied with NBTHK Tokubetsu hozon paper.

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Appraisal Quiz #230 (February 22, 2013)
Who made this sword do you think ?
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hints. ※The picture will be enlarged

Katana
Blade length : 74.7 cm or 29.40 inches.
Sori : 0.8 cm or 0.31 inches.
Mekugi : 1
Width at the hamachi : 2.90 cm or 1.14 inches.
Width at the Kissaki : 1.89 cm or 0.74 inches.
Kasane : 0.69 cm or 0.27 inches.
Era : Edo period Kanbun era.
Shape : The blade is regular sized small sori Kanbun shape with rather longer kissaki.
Jitetsu : Itame hada well grained with jinie attach and chikei work.
Hamon : From hamachi area, suguha and then gunome midair with deep nioikuchi and bright hamon in Ha, small sunagashi and Kinsuji work.

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