Previous answer is
Mumei (attributed to Sengo Masashige, 千子正重)

Features: This is a sword attributed to Sengo Masashige.
Masashige was a smith of the Muramasa school, and a disciple of Masashige, who himself was a student of Muramasa.
The swordsmith is from the lineage of the Muramasa school, specifically the Sengo group, and it clearly exhibits the characteristic hamon on both sides of the blade, a hallmark of the Muramasa and Sengo schools.

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Appraisal Quiz #817 (October 19th, 2024)
Who made this sword do you think ?
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Blade length: 2 shaku 2 sun 4 bu 5 rin (68.03 cm / 26.77 in) Curvature: 5 bu 5 rin (1.67 cm / 0.66 in)
Mekugi holes: 2
Width at base (Motohaba): 2.8 cm (1.10 in)
Width at tip (Sakihaba): 2.02 cm (0.79 in)
Thickness (Kasane): 0.7 cm (0.28 in)
Sword weight: 705 grams (1.55 lbs)
Shape: Well-proportioned, wide blade and deep curvature. The tip is extended, giving it a well-balanced and elegant appearance.
Jigane: The forging pattern is an exquisite mix of itame-hada and mokume-hada, with prominent chikei visible. The jihada is well-forged and displays the highest level of craftsmanship, with rich nie grains.
Hamon: The hamon is a suguha base with vigorous ashi, vibrant ha activity, prominent kinsuji, and a mix of sunagashi. The boshi shows a midare pattern with a sweeping kaeri (return).

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Answer will be posted at next Appraisal Quiz.

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